Growth of Sillenite-Structure Single Crystals

V. M. Skorikov; Yu. F. Kargin; A. V. Egorysheva; V. V. Volkov; M. Gospodinov

In this paper, the effect of SiO2 on the growth of BSO crystals under hydrothermal conditions was studied. With the increase of SiO2's concentration doped in the mineralizer, the color of the grown BSO crystals became more pale and the crystallization became better. Moreover the morphology of BSO crystals changed from that with {111} and {112} facets mainly presented to

The structural, electronic, optical, and magneto-optical properties of the three Bi 12 MO 20 sillenites (BMO; M ¼ Ti, Ge, and Si) have been investigated on the basis of the first-principles calculations performed by the full potential augmented plane wave method. The BMO's linear optical responses are found to be very similar, but their optical rotatory powers and Faraday ellipticities exhibit notable differences in both visible and ultraviolet parts of the spectra. These differences originate from the subtle differences within the BMO's electronic structures, such as different band-gaps and different offsets of the valence band tops. The latter are found to be caused not by the influence of the M ion electronic states, but by particular behavior of the M-O and the Bi-O chemical bonds. V

Inorganic Materials, Vol. 41, Suppl. 1, 2005, S24–S46. Original Russian Text Copyright © 2005 by Skorikov, Kargin, Egorysheva, Volkov, Gospodinov. Growth of Sillenite-Structure Single Crystals V. M. Skorikov*, Yu. F. Kargin*, A. V. Egorysheva*, V. V. Volkov*, and M. M. Gospodinov** * Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia ** Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko ch. 72, Sofia, 1784 Bulgaria e-mail: anna_egorysheva@rambler.ru Abstract—The main processes for preparing bulk single crystals and films of photorefractive and piezoelectric Bi12MxO20 ± δ (M = Group II–VIII elements) sillenite compounds are considered. Experimental data are summarized on the crystal growth of Bi12MxO20 ± δ from the melt and under hydrothermal conditions, and the key morphological features of sillenites are analyzed. Various types of macroscopic growth defects in sillenite-type crystals are described, and their origin is discussed. The compositions of second-phase inclusions in undoped and doped (Group I–VIII elements) Bi12SiO20, Bi12GeO20, and Bi12TiO20 single crystals are presented, and the main physicochemical properties of various Bi12MxO20 ± δ crystals are summarized. INTRODUCTION Crystals of the sillenite-structure bismuth oxide compounds Bi12MO20 (M = Ge, Si, Ti) offer a high-speed photorefractive response in the visible range [1–4] and possess good piezoelectric and electro-optic properties [5] and high optical activity [6]. They are used as materials for wave front amplification, conjugation, and self-conjugation systems, adaptive holographic interferometers, spatial-frequency filters, photodetectors, and other dynamic holography devices [1–4, 7, 8], and also for bulk and surface acoustic wave devices (filters, delay lines, and others) [9] and electric/magnetic field sensors [10, 11]. Bi2O3-based phases isostructural with γ-Bi2O3 (mineral sillenite) are called sillenites [12]. Bi12MxO20 ± δ (M = Group II–VIII elements) sillenite-structure compounds exist only in systems containing bismuth oxide. Phase-equilibrium studies of Bi2O3–MxOy systems demonstrate that sillenite phases occur at M = Rb, Mg, Zn, Cd, B, Al, Ga, In, Tl, Si, Ge, Ti, Pb, P, V, As, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, Ru, and Ir and may be stable or metastable compounds or γ-Bi2O3-based solid solutions, depending on composition. To date, about 60 Bi12MxO20 ± δ compounds with various Mn+ cations (or [M3+M5+], [M2+M5+], and [M2+M6+] combinations) and numerous solid solutions between such compounds have been synthesized [13, 14]. The first structural study of a sillenite phase, bismuth germanate, was carried out by Abrahams et al. [15]. Later, the crystal structure of sillenites was studied extensively [16–22]. Bi12MxO20 ± δ crystals have a cubic structure of pentagontritetrahedral symmetry (sp. gr. I23 = T 3, Z = 2), with five sets of equivalent positions of site symmetry T(1), D2(3), C3(4), 2C2(6), and C1(12). The coordinates and point symmetry of equivalent positions in space group I23 can be found in [19]. Owing to the great diversity of physical effects in sillenite-type crystals and the possibility of employing them in electronic and optoelectronic devices for various technological applications, a wide variety of techniques have been used to grow both bulk single crystals and epitaxial layers (films) of sillenites. Most research effort has been concentrated on Bi12GeO20 (BGO), Bi12SiO20 (BSO), and Bi12TiO20 (BTO) crystals. The approaches most frequently used to prepare BGO, BSO, and BTO crystals are melt growth (Czochralski (CZ), Bridgman, Stepanov, and edge-defined film-fed growth (EFG) processes) [23–80] and hydrothermal crystallization [108–123]. Films of these compounds can be produced by liquid phase epitaxy (LPE), physical sputtering, chemical vapor transport, and solution growth [81–107]. The crystal growth of Bi12MxO20 ± δ compounds with various Mn+ cations (position 2a in the center of [MO4]n– tetrahedra) has received little attention. The main purpose of this paper is to systematize the available information about the growth of sillenite-type single crystals and films. We consider here the basic processes for growing single crystals of various Bi12MxO20 ± δ compounds— not only of the well-studied sillenites with M = Si, Ge, and Ti but also of phases that are essentially unexplored, with various Mn+ cations (Zn, B, Al, Ga, Fe, Tl, P, V) and cation combinations ([Al, P], [Ga, P], [Fe, P], [Fe, V], [Zn, V]). 0020-1685/05/4101-S0024 © 2005 Pleiades Publishing, Inc. S25 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 Fig. 1. BSO and BGO single crystals grown by the CZ technique at the Laboratory of Physicochemical Analysis of Oxides, Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences. T, K L+ Bi14Ti3O12 1170 1130 L Bi12TiO20 PREPARATION OF BULK SINGLE CRYSTALS OF SILLENITE COMPOUNDS BY CZ AND TOP-SEEDED SOLUTION GROWTH (TSSG) PROCESSES The first growth of large BGO single crystals was reported in 1967 by Ballman [23]. BTO single crystals were first grown in 1966 by Skorikov at the Laboratory of Physicochemical Analysis of Oxides, Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences. Their properties were described in [24]. The main process for preparing single crystals of the congruently melting compounds BGO and BSO is CZ growth [25–62]. Vertical Bridgman growth of BSO and BGO single crystals was described in [63– 65]. Incongruently melting compounds, e.g., BTO, are commonly grown from nonstoichiometric melts containing an excess of one component (TSSG process) [66–80]. Most BSO and BGO single crystals for acoustic and optical applications are grown by CZ pulling. Using this technique, BSO and BGO single crystals 50–70 mm in diameter and up to 400 mm in length have been grown (Fig. 1). When single-crystal seeds are not available, crystals can be grown onto a Pt filament, with one or several necks to ensure single-crystal growth. To prepare large single crystals, use is made of (100), (110), and (111) seeds, and the crystals are commonly pulled from Pt crucibles in air. The crystal growth of BSO and BGO in argon and oxygen atmospheres was described by Mokrushina et al. [8] and Piekarczyk et al. [37]. The crucible and growth charge can be heated using an rf generator or resistance furnace. The stoichiometric melt composition for BSO and BGO crystal growth is Bi2O3 : SiO2 (GeO2) = 6 : 1. BSO and BGO crystals can also be grown from nonstoichiometric melts, for example, BixSiO1.5x + 2 with x = 10–14 (x = 11.77–12.05 in the grown crystal [39]) or 8–24 mol % GeO2 [61]. CZ growth was also used to prepare crystals of the congruently melting compounds Bi24GaPO40 (BGaPO), Bi24FePO40 (BFePO), and Bi24GaVO40 (BGaVO). The conditions for growing various Bi12MxO20 ± δ single crystals are summarized in Table 1 [80]. Single crystals of incongruently melting compounds, such as BTO, Bi24AlPO40 (BAlPO), Bi25FeO39 (BFeO), Bi25GaO39 (BGaO), Bi24B2O39 (BBO), Bi38ZnO58 (BZnO), and Bi36ZnV2O60 (BZnVO), can be grown by the TSSG process from nonstoichiometric melts containing an excess of one component. BTO single crystals can be grown from nonstoichiometric Bi2O3–TiO2 melts containing 4.5 to 12 mol % TiO2 [66]. To locate the homogeneity range of bismuth titanate, Volkov [68] and Egorysheva et al. [73] prepared BTO single crystals from charges corresponding to different liquidus temperatures (4–10 mol % TiO2). As the TiO2 content of the growth charge decreases from 10 to 4 mol %, the lattice parameter of the grown L + Bi12TiO20 1090 1065 1050 ~ Bi2O3 ~ ~ 2 4 6 8 10 mol % TiO2 12 14 15 Fig. 2. Homogeneity range of BTO [68]. BTO crystals increases from 10.170 to 10.176 Å. The lattice parameter of a BTO crystal grown from a hydrothermal solution corresponding to 14 mol % TiO2 was reported to be a = 10.169 Å [115]. According to Volkov [68], the homogeneity range of bismuth titanate extends from 13.2 to 14.28 mol % TiO2 (Fig. 2). At the same time, Miyazawa and Tabata [72] assume, also based on the variation of the lattice parameter with melt composition, that the solidus curve of BTO has a retrograde character. The first attempts to grow BZnO, BGaO, and BBO crystals were reported by Bruton et al. [66, 67]. They, however, failed to obtain perfect crystals. A serious impediment to the preparation of large BZnO, BFeO, BGaO, and BBO single crystals by TSSG is that these compounds crystallize in rather narrow temperature and composition ranges. The temperature range of S26 SKORIKOV et al. Table 1. Conditions for melt growth of sillenite-type single crystal Compound Charge composition Pulling rate, mm/h Rotation rate, rpm Diameter, mm Length, mm Inclusions Bi12SiO20 6Bi2O3 : 1SiO2 1–3 8–25 20–40 250 δ*-Bi2O3 , Bi2SiO5 , Pt Bi12GeO20 6Bi2O3 : 1GeO2 1–3 8–25 20–40 250 δ*-Bi2O3 , Bi2GeO5 , Pt Bi12Ti0.9O19.8 6–9 mol % TiO2 0.8–2 8–30 10–40 50–80 δ*-Bi2O3 , Bi4Ti3O12 , Pt Bi38ZnO58 11 mol % ZnO 0.3–1.2 30–50 8–12 10–20 ZnO, Pt, Bi2Pt2O7 Bi25GaO39 8–10 mol % Ga2O3 0.3–2.5 30–50 8–12 10–25 Bi2Ga4O9 , (BiPtGaO)a, Pt Bi25FeO39 10–12 mol % Fe2O3 0.3–2 20–40 8–12 10–15 BiFeO3 , Pt Bi24B2O39 16.5 mol % B2O3 0.3 20–40 7–10 8–15 Bi24AlPO40 5–7.7 mol % AlPO4 1–3 20–50 8–14 20–30 Bi2Al4O9 , Pt Bi24GaPO40 12Bi2O3 : 1GaPO4 1–2 20–45 10–15 20–30 Bi5PO10 , Bi2Ga4O9 , Pt Bi24FePO40 12Bi2O3 : 1FePO4 1–2 20–45 8–12 15–20 δ*-Bi2O3 , BiFeO3 , Pt Bi24GaVO40 12Bi2O3 : 1GaVO4 0.8–1.5 15–30 6–8 10–15 Bi2Ga4O9 , Pt Bi36ZnV2O60 7.7 mol % ZnO, 0.2 0.4 6–8 10–15 ZnO, Pt Pt 3.3 mol % V2O5 Note: a Exact composition is unknown. crystallization between the eutectic and peritectic was reported to be 735–755°C (20°C) for BZnO, 770– 785°C (15°C) for BFeO, and 795–810°C (15°C) for BGaO [124–126]. The respective composition ranges of crystallization are 9.1–14.3 mol % ZnO, 5–16 mol % Fe2O3, and 5–11 mol % Ga2O3. As shown by Kargin [14], the homogeneity ranges of BGaO and BZnO are about 2 mol % in width. BBO crystallizes between 622 and 628°C (6°C) in the composition range 16.5–19.0 mol % B2O3 [127]. The high melt viscosity also impedes the preparation of high-quality BBO single crystals. To reduce the melt viscosity and extend the temperature range of crystallization, Burianek and Muhlberg [76] attempted BBO crystal growth in the ternary system Bi2O3–B2O3–Li2O. This markedly reduced the amount of second-phase (Bi4B2O9) inclusions, but they failed to obtain BBO single crystals of optical quality (without inclusions). The crystal growth conditions for BZnO, BBO, BGaO, BFeO, BAlPO, and BZnVO were optimized in [77, 79, 80] (Table 1). The maximum pull rate depends on the melt composition, crystal size, and temperature gradients over the melt [36, 38]. Brice [36] analyzed the axial and radial temperature gradients for isotropic growth of bismuth silicate single crystals. According to his results, the maximum axial temperature gradient for crystals up to 50 mm in diameter is given by dt  78  --- ---------, °C/cm,  dz max R 3/2 dt where ----- is the axial temperature gradient over the dz melt and R is the crystal radius (cm). Figure 3 shows a plot of the calculated maximum temperature gradient versus crystal radius for the growth of homogeneous, crack-free crystals. For example, the maximum gradient for crystals 1 cm in radius is 50°C/cm, and the theoretically predicted value is 76°C/cm. The maximum cooling rate of bismuth silicate crystals after the growth process is 64/R2 (°C/h) at their melting point and a factor of 2 slower near room temperature [36]. The rotational instability of bismuth-containing oxide melts in BSO and BGO crystal growth was investigated in [38, 40, 44, 48, 57, 58, 60]. The crystal rotation rate during pulling was shown to have a strong INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS ω=O 500 Maximum gradient, °C/cm S27 200 100 50 20 10 ω < ωc 0 0.5 1.0 1.5 2.0 2.5 Crystal radius, cm Fig. 3. Maximum permissible axial temperature gradient as a function of crystal radius [36]. effect on the melt flow pattern and, accordingly, on the shape of the crystal–melt interface. Changes in fluid flow can be related to the Reynolds number [128], ω > ωc Re = R ω/ν, 2 where R is the crystal radius, ω is the crystal rotation rate, and ν is the kinematic viscosity of the melt. Increasing the Reynolds number to above the critical value Rec sharply changes the flow pattern and the shape of the crystal–melt interface (Fig. 4). Experimental data suggest that Rec decreases with decreasing pull rate and increases with temperature gradient. Rec also depends on the melt height. Studies of rotational instability in the CZ growth of bismuth silicate and bismuth germanate crystals have shown that the instability arises from the combined effect of the radial temperature gradients and the destabilization of the crystal-rotation-induced vertical gradients in the melt [38, 40, 44, 48]. Beyond the critical crystal rotation rate, the crystal detaches from the melt. The interaction between the crystal-driven and convective flows changes the sign of the vertical gradient under the crystal and, as a consequence, increases the radial heat flow. Simulation studies of heat and mass transfer processes during CZ pulling of BSO and BGO crystals in real systems demonstrate that the axial and radial heat transfer processes have a significant effect on crystal morphology if there are changes and fluctuations of heater power [57, 58, 60]. The effect of growth conditions on the shape of the crystal–melt interface was studied by Volkov [68]. According to his results, the interface is convex in rfheated systems at seed rotation rates from 2 to 20 rpm and pull rates from 2.5 to 3.5 mm/h. Resistive heating INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 Fig. 4. Effect of crystal rotation rate on the melt flow pattern [128]. typically results in a concave growth interface, leading in some instances to the growth of crystals containing cylindrical cavities. Figure 5 shows different shapes of the crystal–melt interface during pulling of bismuth titanate single crystals. Under normal growth conditions, Volkov [68] obtained BTO crystals up to 20 mm in diameter and 30–40 mm in length. Crystals of sillenite compounds have a pronounced tendency toward faceting. Typical habits of bismuth silicate and bismuth titanate crystals and their stereographic projections are displayed in Fig. 6. Faceting at low pull rates is characteristic of incongruently melting compounds, such as BTO, BGaO, and BZnO. In the crystal growth of the congruently melting compounds BSO and BGO at low thermal gradients (<40°C/cm) and pull rates below 2.5 mm/h, the crystal–melt inter- S28 SKORIKOV et al. I II III IV Melt Fig. 5. Shapes of the growth front corresponding to the crystal growth of bismuth titanate by different mechanisms: (I−III) growth fronts corresponding to rounded crystals and nearly isotropic surfaces; (I) convex, (II) almost flat, and (III) concave growth fronts; (IV) flat growth front corresponding to the formation of an atomically smooth interface on the (100) singular facet [68]. face is also faceted [28], but conditions for nearly isotropic growth can readily be ensured. INHOMOGENEITIES IN SILLENITE-TYPE CRYSTALS Optical inhomogeneities in the form of striations (up to 1–2 mm in width, with a high concentration of inclusions) are commonly attributed to constitutional supercooling and temperature fluctuations at the growth interface [27–29, 31–33, 75]. Melt growth of small (8 × 6 × 12 mm) BSO crystals under near-equilibrium conditions [34] shows however that the optical inhomogeneity cannot be explained solely by growth rate instability and anisotropy. Steiner et al. [34] suppose that the periodic optical inhomogeneity in faceted crystal growth is associated with deviations from stoichiometry within the homogeneity range of the crystal [1 [1 10 ] 00 ] A question of major importance in the melt growth of sillenite compounds is the optical homogeneity of single crystals [27–52]. The two most typical “optical” defects in sillenite-type crystals are second-phase inclusions and regions differing in optical absorption. Increased-absorption regions in bismuth silicate and bismuth germanate crystals may appear as striations and a so-called central core, which is seen as a dark area in the central part of cross sections (Fig. 7). It is commonly believed [29–41, 59] that the central core and selective decoration in the shape of a Maltese Cross for the [100] and [110] growth directions or in the shape of a three-bladed propeller for the [111] growth direction (Fig. 8) are associated with growth rate anisotropy and the difference in the distribution coefficient of “photochromic” impurities between the polar and nonpolar facets of the growth interface. If the interface has the form of a flat (100) facet (usually in faceted growth at fast crystal rotation rates), there is no central core [33, 68]. Layer-by-layer (faceted) growth of BTO single crystals occurs in the [100] and [110] directions, when the growth interface can be represented by a singular facet (Fig. 9). The crystal habit of BTO is governed by the pull direction (Fig. 10). (0 01 ) (0 11 ) – (112) – (100) 01 ) 10 (1 – 100 –– 110 – 011 – 010 – 131 – 121 – 100 – 105 – 101 001 – 112 – 211 (1 –– 230 – 010 – 211 – 320 110 100 (‡) – 100 –– 232 – – 236 – 011 023 105 101 ) 12 ––– (111) –– 210 – 110 – 121 – 112– – 011 131 010 ] 11 [0 (011) (0 –– (110) – (101) – (112) ) ) 10 (0 – (110) – 320 – 336 – 101 – 203 001 – 210 – 320 – 232 236 023 011 236 203 101 – 210 010 323 320 210 100 (b) Fig. 6. Growth habits and stereographic projections of (a) bismuth silicate and (b) bismuth titanate crystals. INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS (‡) (b) (c) (d) S29 Fig. 7. Central core in cross sections of BSO and BGO crystals grown in the (a) [100], (b, d) [110], and (c) [111] directions. and with the variation in impurity concentration due to small temperature fluctuations. Note that precision measurements on samples cut from the seed and tail ends of BSO and BGO single crystals about 400 mm in length revealed no differences in density or lattice parameter [13, 14], suggesting that both compounds have an insignificant homogeneity range, in contrast to what was reported by Hill and Brice [39]. According to Zhereb and Skorikov [129], the chief cause for absorption variations in BSO, BGO, and BTO crystals, after minimizing the effect of the above-mentioned factors, is the existence of metastable phase equilibria in the corresponding systems. During cooling, a metastable melt Lm may undergo two types of transformations into a stable state: Lm Lst Sst, (1) Lm Sm Sst. (2) In process (1), the structure of the metastable melt Lm transforms into a stable structure (Lst) in the liquid state, and this transition has no impact on the crystal growth of the stable compound Sst. In process (2), the INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 exothermic transition of a metastable crystalline phase Sm to a stable state changes the thermal conditions at the growth interface. A high stability of metastable phases may result in the capture of such phases in the form of inclusions by the growing crystal of the stable compound [13, 14, 30, 129]. Kargin [14] and Voskresenskaya et al. [30] determined the composition of inclusions in nominally undoped and doped sillenite-type crystals by x-ray microanalysis and x-ray diffraction (XRD). The results are summarized in Tables 1 and 2. Figures 11 and 12 show x-ray scan images of samples containing inclusions of platinum metal, impurity phases, and oxide dopants. The formation of metallic platinum inclusions in Bi12MxO20 ± δ crystals is associated with the high reactivity of bismuth-containing oxide melts, which react with most inert materials. Studies of chemical interaction between platinum and liquid bismuth-containing oxides demonstrate that the dissolution rate of Pt in Bi2O3–MxOy (M = Zn, Cd, B, Ga, In, Si, Ge, Ti, Sn, P) melts may be limited by the following processes: (1) surface oxidation of platinum, (2) dissolution of the S30 SKORIKOV et al. (‡) (b) 〈100〉 〈100〉 〈110〉 + 〈110〉 + - - _ 〈101〉 〈001〉 〈001〉 〈101〉 (c) _ 〈211〉 _ 〈110〉 _ _ 〈121〉 〈101〉 〈110〉 〈111〉 Fig. 8. Morphology of the crystal–melt interface in the crystal growth of BSO along (a, b) 〈001〉 and (c) 〈111〉 directions and the corresponding cross-sectional selective decoration patterns [41]. oxide film in the melt, and (3) diffusion of the dissolution products from the liquid–solid interface [65]. At 1270 K, the oxide film on platinum consists of PtO, Pt3O4, and PtO2, and its thickness is several tens of microns. The phase composition of the oxide film depends on temperature: above 1470 K, the predominant phase is PtO. In addition, the oxide film was found to contain Bi2PtO4, resulting from the reaction of PtO with the melt. An applied dc electric field has a significant effect on the dissolution behavior of platinum, which indicates that platinum dissolution in bismuthcontaining oxide melts follows an electrochemical mechanism. At slow stirring rates (ω), the dissolution rate of platinum in Bi2O3–MxOy melts (Fig. 13) is limited by the diffusion of the reaction products. At high values of ω, the rate-controlling process is the chemical reaction proper (the dissolution rate is independent of the stirring rate). The transition from diffusion to kinetic control is accompanied by an inversion of the temperature dependence of the dissolution rate because the reaction is exothermic. Experimental studies demonstrate that Pt solubility in Bi2O3–MxOy melts decreases with increasing temperature and that the maximum in the Pt solubility in Bi2O3–B2O3 melts at 1020 K is due to the precipitation of Bi2Pt2O7, which decomposes at higher temperatures to form Bi2O3, Pt, and oxygen. The micrograph in Fig. 14 shows Pt dendrites in a BSO single crystal. Bi12MxO20 ± δ single crystals are enantiomorphous. Melt growth typically yields right-handed crystals, which rotate the plane of incident linearly polarized light clockwise (when viewed head-on). To grow levorotatory Bi12MO20 (M = Si, Ge, Ti) crystals, Kargin 1 et al. [130] used seeds 1–2 mm in size prepared by spontaneous crystallization in hydrothermal solutions. Dextro- and levorotatory seeds were separated using a 1 polarizing microscope. As a result, they obtained BSO, BGO, and BTO single crystals of good optical quality, up to 60 mm in length and 15–20 mm in diameter. Optical rotatory dispersion measurements showed that the two enantiomorphs were identical in the amount of rotation. Attempts to grow racemic (optically inactive) Bi12MO20 crystals using a composite seed consisting of right and left forms were unsuccessful: the result was a bicrystal with a well-defined boundary between its dex1 tro- and levorotatory parts [14]. Growth defects in BSO and BGO crystals were studied in [34, 43, 131–133] by x-ray topography, which revealed well-defined inclusions, striations, and stacking faults. Dislocations in BSO and BGO crystals can be revealed by selective chemical etching [62, 134] or annealing in a reducing atmosphere (2–5% H2 + 98−95% N2) [41, 135]. The best selective etchants for BSO and BGO wafers of various orientations are nitric acid solutions and ethanolic solutions of bromine [134]. The dislocation density in bismuth silicate and bismuth germanate crystals varies from 102 cm–2 in “defectfree” regions (Fig. 15) to 5 × 104 cm–2 in regions containing inclusions [134]. The temperature range of plasticity for BSO is about half as broad as that for BGO, and the critical stress for dislocation generation at the melting point is 0.5 and 1 MPa, respectively [136]. Crack nucleation in BSO and BGO crystals begins at stresses on the order of 7 MPa. The index of refraction in stress concentration zones differs from that in relatively perfect zones of crystals by up to 2 × 10–3. The anomalous birefringence in regions containing second-phase inclusions attains 2.0 × 10–5 in BSO and 1.4 × 10–5 in BGO, whereas that in defect-free regions is within 5.0 × 10–6 [136]. INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS S31 The charge for the crystal growth of BSO, BGO, and BTO is commonly synthesized from high-purity chemicals, e.g., OSCh 13-3 Bi2O3, OSCh 12-4 SiO2, extrapure-grade GeO2, and OSCh 9-3 TiO2. According to laser ionization mass spectrometry data [31], BSO and BGO crystals contain unintentional impurities at a level of 1–10 ppm by weight: Na, K, Mg, Ca, Al, P, Fe, Mn, Cl, F, and S. In the region of the central core, the concentration of “bleaching” impurities (Al, Ca, Mg, P, Cl) is typically lower, and that of “coloring” impurities (Fe, Mn, Ni, Co) is higher. CZ BSO crystals differ markedly in contamination level from hydrothermally grown crystals: GROWTH OF DOPED BSO, BGO, AND BTO CRYSTALS Doping of Bi12MO20 (M = Si, Ge, Ti) crystals with elements in different valence states has a significant effect on their optical, photoelectric, and acoustic properties. Dopants in the form of oxides or bismuth oxide compounds (e.g., BiPO4) can be introduced into a stoichiometric charge for BSO and BGO growth and a charge containing 8–10 mol % TiO2 for BTO growth. The dopant content of the growth charge is typically in the range 0.001–1.0 wt % (Table 2). Impurity Na K Mg Ca Al Ga V Cr Mn Fe CCZ , ppm 1 3 2 5 2 ND 0.05 0.5 ND 0.5 CHT , ppm 0.7 0.07 20 4 0.4 0.1 2 0.02 7 50 Note: ND = not detected; HT = hydrothermally grown. Table 2 lists the compositions of impurity phases captured by growing single crystals at dopant concentrations above the solubility limit. Experimentally determined effective distribution coefficients of impurities in doped BSO, BGO, and BTO crystals have been reported in only a few papers [29, 74, 123, 137]. In most reports, only the dopant concentration in the growth charge is specified. Leigh et al. [123] reported that, in the bismuth silicate crystals (‡) grown from melts containing 0.1, 0.01, and 0.15 wt % M2O3 (M = Al, Ga, B), the doping level was 0.008, 0.004, and 0.001 wt % M, respectively. In bismuth germanate, impurities differ markedly in distribution coefficient: 0.08 for Ga, 0.22 for Al, <0.1 for Zn, 1.1 for P, 1.8 for Cr, and 5 for Pb. Grabmaier and Oberschmid [137] determined the distribution coefficients of some impurities in the CZ growth of BGO (BSO) crystals: 0.22 (0.2) for Al, 0.08 (0.16) for Ga, 1.2 (5.5) for P, (b) Fig. 9. Shape of the growth interface in the crystal growth of BTO in the (a) [100] and (b) [110] directions. INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 S32 SKORIKOV et al. Seed 1 1 2 2 3 3 001 1–1 Crystal Melt 011 011 2–2 013 013 011 011 3–3 013 001 011 013 011 001 Fig. 10. Changes in the morphology of the crystal–melt interface in the crystal growth of BTO [68]. 5 for Pb, 1.8 for Cr, 0.08 for Nd, <0.1 for Zn, <0.05 for Fe, <0.4 for Eu, and <0.2 for Te. The distribution coefficients of impurities in bismuth titanate crystals were reported by Kargin et al. [74]: 0.4 for Zn, 0.1 for Cd, 0.9 for Cu, 0.01 for Ni, 0.6 for Ca, <0.005 for B, 0.8 for Ga, 0.2 for Co, 0.3 for Fe, 1.8 for Cr, 1.6 for Mn, 1.4 for Nb, 1.5 for V, and 0.4 for P. As shown by Kumaragurubaran et al. [62], the dopant composition influences the dislocation density in the crystal. Kargin [14] investigated doped sillenites with the aim of establishing the nature of the resulting solid solutions and the solubility of different dopants. Data on the chemical composition of impurity phases (inclusions) in the doped crystals were used in analyzing phase equilibria in several ternary systems containing BSO, BGO, and BTO. BRIDGMAN GROWTH OF BSO AND BGO CRYSTALS Vertical Bridgman (Obreimov–Shubnikov) growth of BSO and BGO single crystals was described by Xu Xuewu et al. [63, 64]. BSO crystals were grown in a Pt crucible using standard facilities and presynthesized polycrystalline BSO. Seeds, oriented along [100], [110], [111], or [211], were mounted on the bottom of the crucible [63]. The vertical temperature difference was 20–30°C. To INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS S33 Table 2. Inclusions in doped BSO, BGO, and BTO single crystals (x-ray microanalysis data) Compound Dopant Bi12SiO20 (BSO) Weight percent – ZnO 2.0 ZnO, Pt CdO 2.0 CdO, Pt Al2O3 1.0 Bi2Al4O9 , Pt Ga2O3 1.5 Ga2O3 , Pt Fe2O3 1.0 BiFeO3 , Pt Ni2O3 0.008–0.23a NiO, Pt Co2O3 0.0006–0.0025 CoO, Pt BiPO4 2.0 mol Cr2O3 Bi12GeO20 (BGO) Bi12Ti0.9O19.8 (BTO) Inclusions %a 0.001–0.01 Bi5PO10 , Pt Bi16CrO27 , BiCrO3 , Pt V2O5 0.22 (in terms of V) δ*-Bi2O3 ZnO 2.0 mol %a ZnO, Pt CdO 2.0 mol %a CdO, Pt Ga2O3 1.5 mol %a Ga2O3 , Pt ZnO 0.1 ZnO, Pt, Bi4Ti3O12 CdO 0.3a δ*-Bi2O3 , Pt, (BiPtCdO)b Al2O3 0.1 Bi2Al4O9 , Pt Ga2O3 0.2 Bi2Ga4O9 , Pt V2O5 0.5 (in terms of V) δ*-Bi2O3 BiPO4 0.16 (in terms of P) Bi24P2O41 Co2O3 0.0006–0.0025 CoO, Pt CuO 0.1 (in terms of Cu) CuO Cr2O3 0.001–0.01 Mn2O3 0.01–0.6a Note: a In the growth charge. b Exact composition is unknown. reduce the asymmetry of the thermal field, the crucible was placed in a tube filled with Al2O3 powder. After partial melting of the seed, the crucible was translated to the low-temperature zone at a rate below 1 mm/h. In this manner, BSO crystals 35 × 35 mm in cross section and 150 mm in length were prepared. In contrast to CZ pulling, the Bridgman process rules out anisotropic radial growth because the crosssectional configuration of the crystal is determined by the shape of the crucible. However, since the linear thermal expansion coefficient of BSO (16 × 10–6 K–1) is much larger than that of Pt (9.6 × 10–6 K–1), the nonuniform temperature field in the growing crystal gives rise to significant thermal stress. INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 The BSO crystals grown in the [100] and [110] directions had a central core throughout their length. The cross-sectional area of the colored region was 25 to 50% of that of the crystal. The crystals grown along [111] and [211] had no core. In the CZ growth of Bi12MO20 crystals along [100] and [110], core formation can be avoided under faceted growth conditions if one facet occupies the entire interface. Such conditions are, however, difficult to achieve in Bridgman growth because of the thermal asymmetry. Ensuring a symmetrical thermal field in the furnace, one can achieve a concave crystal–melt interface, corresponding to isotropic growth. This will minimize the dimensions of the core, but the concave interface will lead to increased stress and dislocation density, block formation, and microc- S34 SKORIKOV et al. (‡) (b) (c) (d) (e) (f) (g) (h) (j) (m) (k) (n) (i) (l) (o) Fig. 11. (a, c) Si Kα, (b, d, g, l) Bi Mα, (e, f, i, j) Pt Mα, (h) Ge Kα, (k) Zn Kα, (m) Ni Kα, (n) P Kα, and (o) Cu Kα x-ray maps of inclusions in (a–f) undoped BSO, (g–j) undoped BGO, and (k, l) ZnO-, (m) NiO-, (n) P2O5-, and (o) CuO-doped BSO single crystals; composition of inclusions: (a, b) Bi4Si3O12, (c, d, g, h) δ*-Bi2O3, (e, f, i, j) Pt metal; 100 × 80 µm viewing field. racking. Detailed investigation showed that, in [111] crystal growth, the interface was slightly convex [63]. Thus, the results reported by Xu Xuewu et al. [63] indicate that optical-quality BSO crystals can be prepared by Bridgman growth in the [111] and [211] directions at solidification rates under 1 mm/h. Characteris- tically, Bridgman-grown crystals have a lower dislocation density in comparison with CZ growth and show a uniform cross-sectional coloration. Because of the slow growth rate, slightly convex crystal–melt interface, and relatively high stability of the thermal field, such crystals are free of striations. However, in spite of these INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS advantages, the Bridgman method has not found wide application in the growth of sillenite-type crystals. The equilibrium distribution coefficients of impurities in the Bridgman growth of BSO crystals are 0.0144 for Ni, 0.1621 for Sb, 0.7036 for V, 0.0392 for Nb, 0.0765 for Ta, and 0.976 for P [64]. (‡) S35 MELT GROWTH OF SILLENITE-TYPE CRYSTALS BY OTHER METHODS In addition to the crystal growth techniques considered above, several other processes for the melt growth of sillenite-type crystals have been reported in the literature. (b) (c) (d) (e) (f) (g) (h) (i) (j) Fig. 12. (a, c, g) Bi Mα, (b) P Kα, (d) Al Kα, (e, f) Ga Kα, (h, j) Pt Mα, and (i) Zn Kα x-ray maps of inclusions in (a, b) BGaPO (Bi5PO10 inclusion), (c, d) BAlPO (Bi2Al4O9 inclusion), (e–h) BGaO (δ*-Bi2O3, Ga2O3, and Pt inclusions), and (i, j) BZnO (ZnO and Bi2Pt2O7 inclusions) single crystals; 100 × 80 µm viewing field. INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 Dissolution rate, mg/(cm2 s) S36 SKORIKOV et al. 0.04 1 2 3 4 II 0.03 0.02 I 0.01 4 6 8 10 ω, s – 1/2 Fig. 13. Dissolution rate of Pt in (I) 6Bi2O3 · GeO2 and (II) 6Bi2O3 · ZnO melts as a function of the square root of the stirring rate at (1) 1070, (2) 1170, (3) 1220, and (4) 1270 K; initial Pt content, 0.01 wt % [65]. Fig. 14. Metallic Pt inclusions in a BSO crystal; 1.0 × 0.5 mm viewing field. Maida et al. [138] described the crystal growth of BSO by a pulling-down method. This growth process is essentially a modification of the Verneuil method and consists in continuously pouring presynthesized powder material into a Pt funnel located in the hot zone of a furnace, where the material melts and drips through a hole onto the top face, covered with a melt layer, of a rotating single-crystal seed, which is slowly lowered to the cold zone of the furnace by a special drive system. If the powder consumption is matched to the lowering rate, the thickness of the melt layer remains virtually constant. This process was successfully used to grow BSO crystals up to 50 mm in diameter and 60 mm in length onto a [111]-oriented seed at a lowering rate of 0.75 mm/h and rotation rate of 20 rpm. To compensate for Bi2O3 vaporization, the starting mixture was slightly enriched in bismuth (14.1 mol % SiO2). The crystals prepared by this process from stoichiometric powder (14.28 mol % SiO2) were found to contain Bi4Si3O12 inclusions and gas bubbles. The presence of the latter was attributed to the difference in composition between the melt and growing crystal. The growth interface was slightly convex. The dislocation density was 4 × 103 cm–2, which is comparable to that in CZ crystals. As pointed out by Maida et al. [138], this process offers the possibility of growing crystals whose diameter is independent of the crucible size, and, owing to the flat shape of the interface, maintained throughout the growth run, makes it possible to circumvent difficulties inherent in the CZ and Bridgman growth of sillenite compounds. One advantage of vertical float zoning over other growth processes is that there is no melt–crucible reaction. This approach was used to prepare BGO and BSO crystals up to 40 mm in length and 1.5–5 mm in diameter [103, 104, 106]. The ability to prepare perfect single crystals by this process depends crucially on symmetric heating and the heater translation rate, determined by the crystal diameter [103]. According to Quon et al. [104], the optimum width of the molten zone is 3 mm. A serious problem in float-zone crystal growth is Bi2O3 vaporization and subsequent deposition on the furnace wall, which distorts the symmetry of the thermal field. Fu and Ozoe [105] optimized the synthesis of the material for feed rods, whose quality has a significant effect on the structural perfection of the crystals. Lan et al. [139] reported the crystal growth of BSO using a combination of CZ pulling and float-zone growth: “zone-melting CZ growth.” A key feature of this method is the use of two (outer and inner) crucibles. The outer crucible contains a melted feed material in such an amount that the crucible can accommodate another, inner crucible, also filled with feed material. The outer crucible can be translated vertically in the furnace across the hot zone, which is several times shorter than the height of the outer crucible. This design allows the narrow molten zone to be moved along the outer crucible as the crystal is pulled. The inner crucible is intended to reduce the concentration of gas bubbles in the growing crystal. One advantage of this method is the possibility of growing crystals highly uniform in diameter, which is determined by the temperature profile in the hot zone. Unfortunately, this method is too complex for commercial application, and the presence of gas bubbles is an inherent feature of the BSO crystals thus grown. Laser-heated pedestal growth and optically heated float-zone growth of thin (1 × 1 mm in cross section) BSO and BTO crystals were described in [101–106]. Maffei et al. [107] reported on the float-zone crystal INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS S37 (‡) (‡) (b) (b) Fig. 15. (a) Etch pits and (b) low-angle boundaries on the (100) face of BSO; 240×, Br2 + C4H9OH + NaBr etch [134]. growth of BGO in microgravity conditions (mission STS-77). PREPARATION OF Bi12MO20-BASED EPITAXIAL STRUCTURES AND PLANAR WAVEGUIDES The processes for epitaxial growth of Bi12MO20 plates and waveguides were described in [81–87]. Single-crystal BSO ribbons can be produced by the Stepanov method or EFG process [88–90]. To grow thin films on BGO, single-crystal sapphire, zirconia, quartz, and other substrates, use is made of rf, plasma, and diode sputtering [91–93] and laser deposition [94–97]. Sillenite-type films were also grown by chemical vapor transport (BGO) [98], metalorganic chemical vapor decomposition (BSO) [99], deposition from aqueous solutions (Bi12MO20, M = Si, Ge, V, As, P) [18], and sol–gel processing (BSO) 100]. Ballman et al. [81] were the first to use LPE for producing single-crystal BSO, BTO, BGaO, BZnO, and BFeO films by dipping a bismuth germanate seed in an appropriate melt (the melting point of BGO is higher INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 Fig. 16. As-grown BTO〈Cu〉 epilayers on (a) (100) and (b) (111) BSO substrates. than those of bismuth titanate and other sillenite compounds). They obtained BTO epilayers about 100 µm thick at growth rates of 1–2 µm/h. The choice of film composition is determined primarily by the condition that the refractive index of the film be greater than that of the substrate material. To obtain a high-quality epitaxial film, it must have small lattice and thermal expansion mismatches with the substrate material. In epitaxial growth, special attention must be paid to the surface condition of the substrate and the homogeneity of the hot zone on the melt surface. A similar process was used by Tada et al. [82] to produce BSO layers codoped with Al and Ca. LPE growth of bismuth titanate layers, undoped and doped with V, Cu, and Ca + Ga, on (100), (110), and (111) BGO and BSO substrates (20 × 30 × 2 mm) was described by Bondarev et al. [84] and Kargin et al. [87]. On (111) substrates, no single-crystal layers were obtained (Fig. 16). The layers were 50 to 150 µm in thickness and were then thinned to 30 µm by mechanical grinding and polishing with diamond pastes. Studies of two-beam-coupling in index gratings in the planar waveguides thus produced showed that the refrac- S38 SKORIKOV et al. tive index had a parabolic profile near the waveguide– substrate interface, attesting to substrate dissolution in the film in the interfacial layer. BTO epilayers were also prepared by close-spaced geometry growth [83] on (110) single-crystal BGO wafers 1–2 mm in thickness and 20 × 20 mm2 in area. To this end, an appropriate amount of bismuth titanate powder (corresponding to a layer thickness of 200−300 µm) was uniformly spread over the substrate surface. Note that layers several microns or tens of microns in thickness cannot be prepared by this process because of the incomplete wetting of the crystal surface by the melt (nonzero contact angle), as a result of which melt drops are formed. The sample was placed in a resistance furnace and heated to the melting point of BTO at a rate no faster than 60 K/h. After a melt layer was formed, the sample was cooled to 1073 K at a rate of 0.1 K/h and then to room temperature at 30–60 K/h. The resultant BTO epilayer was thinned by abrasive grinding and then polished with diamond pastes. In this way, BTO/BGO heteroepitaxial structures were produced, with bismuth titanate layers 30 µm in thickness. The maximum increment of the refractive index in the waveguiding layer was ∆nf = 0.023. The use of rf sputtering for growing thin BSO and BTO epilayers on BGO substrates was described in [91–93]. In contrast to LPE layers, rf-sputter-deposited layers have a tendency to be textured, which impairs their optical quality. Sputtering processes allow deposition of single-crystal films at relatively low substrate temperatures, 650–700 K, which reduces the thermoelastic stress in the deposit. Youden et al. [94, 95] and Alfonso et al. [96, 97] produced thin (≤10 µm) BGO layers on single-crystal sapphire, zirconia, quartz, and other substrates by laser deposition. The results reported by Roszko et al. [86] demonstrate that waveguiding layers can be grown on BGO wafers through metal (Pb and Ni) diffusion. Thin single-crystal ribbons were produced in [88–90] by the Stepanov method and EFG process using standard CZ pulling facilities, platinum shapers, and platinum thermal shields. In EFG growth, Miyamoto et al. [90] tested three die designs differing in die-top geometry: planar, concave angular, and concave. At a pull rate of 7 mm/h in the [100] direction, they obtained a bismuth silicate ribbon of good quality measuring 55 mm in length, 1 mm in thickness, and 13 mm in width. They argued that, at low temperature gradients in the growth direction and concave die tops, thin single-crystal bismuth silicate ribbons can be produced. In Stepanov growth, Ivleva and Kuz’minov [88] used flat die tops. The feed material was melted by rf heating with an axial temperature gradient of 80 K/cm, and the melt temperature was maintained with a stability of ±0.3 K. The optimal parameters for the growth of thin bismuth silicate ribbons were as follows [88]: pull rate of 6 mm/h, axial gradient of 25 K, and a minimum possible radial gradient. Increasing the pull rate to 10 mm/h leads to the formation of swirl defects in the central part of the ribbon. At still faster pull rates, second-phase inclusions appear. Chemical vapor deposition of single-crystal bismuth germanate films through the reaction between germanium chloride and bismuth vapor in the presence of oxidant gas (H2O, N2O) was reported by Silvestri et al. [98]. The optical quality of the films was not very high because of the reaction with the substrate in the range 1000–1100 K and texturing. SEEDED CRYSTAL GROWTH OF SILLENITES IN HYDROTHERMAL SOLUTIONS A viable alternative to the melt growth of sillenite compounds is hydrothermal crystallization [108–123]. This method has the advantage of low growth temperatures, which enables the synthesis of phases that decompose in the solid state and, hence, cannot be prepared by melt growth. Hydrothermally grown crystals are, however, substantially smaller (≤15 mm) than CZ or TSSG crystals. Using seeded growth in hydrothermal solutions, one can prepare sillenite compounds in the form of epilayers 5 to 500 µm thick and bulk crystals up to 10 mm thick [114, 115, 118, 119]. Phase-equilibrium studies of Bi2O3–MxOy– M 2' O– H2O (M = Group II–VIII elements, M' = Na, K, Li) systems at high temperatures and pressures provide a physicochemical basis for the synthesis of phases and crystal growth under hydrothermal conditions. Systematic research on the preparation of sillenite-type crystals in such systems was reported in [108–118]. To produce Bi12MxO20 ± δ (M = Ge, Zn, B, Al, Ga, Cr, Mn, Fe, P, V) epilayers, Samoilovich [116] used a hydrothermal synthesis–recrystallization process or tilted reactor method. Experiments were carried out in 300-cm3 reactors at a dissolution temperature of 300– 310°C, pressure of 50 MPa, and temperature difference of 10–60°C, using an aqueous solution of NaOH as the solvent. The starting charge was either an appropriate mixture of components or spontaneously nucleated crystals of the sillenite compound. The oxidant was NaBiO3 or H2O2, and the substrates were (100), (110), and (111) single-crystal BSO plates 1 to 10 cm2 in area. The best epilayers were obtained by the two-step, synthesis–recrystallization process. Mar’in [115] carried out an XRD study of misfit strain in heteroepitaxial growth of sillenites. The significant lattice mismatch between the substrate and layer was shown to result in ∆a as large as 0.1 Å and more. At layer thicknesses from 25 to 50 µm, the lattice parameter a of Bi12MxO20 ± δ was found to be reduced by 0.064–0.132 Å as compared to its relaxed value in bulk (or polycrystalline) material. The largest reduction in a was found in BZnO and BPO layers. Misfit strain INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS 10× (‡) S39 10× (b) Fig. 17. Systems of cracks in (a) BZnO and (b) Bi12PxO20 epilayers [118]. may lead to cracking of the layer, especially in the case of BVO, BPO, and BZnO, which had the largest lattice mismatch with the substrate. The overall direction of bent cracks on the (110) surface of BZnO was [001]. (100) BPO layers were covered with a system of intersecting 〈110〉 cracks (Fig. 17). Cracking typically occurs in relatively thick (≥50 µm) layers. Comparison of hydrothermally grown and CZ BSO crystals [121–123] indicates that the concentration of optical centers responsible for the coloration of sillenites is two orders of magnitude lower in hydrothermal BSO. Hydrothermally grown Bi12MxO20 ± δ (M = Zn, B, Al, Ga, Tl, P, V) crystals were shown to contain isolated, Hydrothermal growth of bulk bismuth silicate single crystals has received the most attention [115, 118]. Growth runs were performed in Teflon-lined 60-l autoclaves, using (100), (111), and (310) platelike seeds 1 × 1 to 3 × 10 cm2 in area, cut from CZ BSO crystals. The seeds differed in surface condition, having lapped, mechanically polished, or chemomechanically polished surfaces. The surface preparation procedure was shown to have no effect on the perfection of the grown layer, presumably because of the partial seed dissolution under steady-state conditions. The morphology and structural perfection of the BSO crystals thus prepared fitted well with the predicted growth behavior of the faces involved [120]. The morphologically stable planes (100) and (110) produced relatively well formed 〈100〉 and 〈110〉 pyramids. The maximum thickness of the overgrown material was 3 mm on the (100) face and 7 mm on (110). In growth runs with sharp changes in temperature and pressure, typical defects were rounded gas–liquid inclusions elongated in the convective flow direction (Fig. 18). As expected, the (111) face grows via interaction of ridgelike and pyramidal forms with the morphology of singular facets. Its pyramid is highly saturated with closed gas–liquid inclusions. The growth rates of principal faces are independent of growth time and are, on average, 0.003–0.02 mm/day on (100), 0.05 mm/day on (110), and 0.07 mm/day on (111). In some instances, needlelike bismuth inclusions 0.01 to 0.1 mm in size are encountered (Fig. 19), which attests to a drop in oxidation potential in the growth medium. INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 (‡) 20× (b) 20× Fig. 18. Gas–liquid inclusions in (a) (100) and (b) (110) growth pyramids of BSO [118]. Vol. 41 Suppl. 1 2005 Notes: * Incongruent melting. ** Decomposition in the solid state. SKORIKOV et al. INORGANIC MATERIALS Compound Bi12SiO20 Bi12GeO20 Bi12TiO20 Bi24BO39 Bi25GaO39 Bi25FeO39 Bi38ZnO58 Bi24AlPO40 Bi24GaPO40 Bi24FePO40 Bi36ZnVO60 Bi12PxO20 Bi24VO41 Bi25TlO39 Lattice parame- 1.0100 1.0145 1.0174 1.0124 1.0180 1.0190 1.0207 1.0146 1.0151 1.0158 1.0194 1.0162 1.0208 1.0216 ter, nm Atoms per cell 66 66 66 65 65 65 64.6 66 66 66 66 67 67 65 Formula units 2 2 2 1 1 1 0.67 1 1 1 0.67 2 1 1 per cell ρx, g/cm3 9.203 9.223 9.066 9.057 9.35 9.27 9.31 9.08 9.12 9.08 9.038 9.081 8.987 9.425 ρmeas, g/cm3 9.196 9.222 9.06 – 9.27 9.21 9.27 9.02 9.08 9.05 – 9.03 8.89 9.33 Melting point, 1173 1196 1148* 901* 1083* 1068* 1038* 1173 1183 1173 1050* 1143** 1038** 1003** K Heat of fusion, 129 139 – – – – – 132 120 115 – – – – kJ/kg Specific heat, 0.244 0.242 0.249 0.240 0.224 0.232 0.219 0.242 0.243 0.245 – – 0.256 0.23 J/(g K) Band gap, eV 3.25 3.25 3.09 2.91 2.99 2.8 2.88 2.99 2.99 3.2 2.91 3.25 3.25 3.1 Transmission 0.4–7 0.4–7 0.42–7 0.44–7 0.44–7 0.45–7 0.44–7 0.42–7 0.42–7 0.45–7 0.42–7 0.44–7 0.45–7 0.44–7 window, µm Rotatory power 22 21 7 21 20 2.8 17 22 21 3.8 7.7 24 ~0 16 (λ = 0.63 µm), deg/mm Verdet’s 0.195 0.199 0.206 – 0.216 – 0.213 – – – – – – – constant, arcmin/(Oe cm) Index 2.5424 2.5476 2.5619 – 2.579 2.5788 2.59 2.54 2.54 2.56 2.592 – – 2.58 of refraction (λ = 0.63 µm) Electro-optic 4.5 4.3 5.7 – 3.6 – 5.2 4.5 4.3 4.4 5.2 – – – coefficient r41, pm/V Thermal expan16.9 16 15.2 14.4 16.7 16.7 16.8 16.3 16.4 16.4 16.2 16.3 16 16.6 sion coefficient 6 –1 ×10 , K Dielectric 52 46 55 – 34 80 63 50 48 52 – 28 48 – permittivity tanδ (1 kHz) 0.05 0.06 0.06 – 0.07 0.19 0.08 0.05 0.05 0.06 0.07 0.08 – Piezoelectric 4.01 3.44 4.82 – 3.72 2.92 3.21 – – – 4.05 2.35 – coefficient 11 d14 × 10 , C/N Electrical ~10–14 ~10–14 ~10–14 ~10–12 ~10–10 ~10–12 ~10–13 ~10–15 ~10–15 ~10–13 ~10–14 – – – conductivity (300 K), S/cm S40 Table 3. Properties of sillenite-type crystals GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS S41 liquid flow processes determining mass and heat transfer and the physicochemical changes in the growth medium (phase transformations through metastable states). The main types of optical inhomogeneities were described (including the composition of second-phase inclusions), and their formation in crystals of sillenite compounds was analyzed. The main physicochemical properties of various Bi12MxO20 ± δ crystals were presented. 50× Fig. 19. Solid inclusions in a BSO layer [118]. noninteracting OH groups whose concentration (1017 to 1019 cm–3) exceeds that in CZ crystals (~1016 cm–3) [140, 141]. BASIC PHYSICOCHEMICAL PROPERTIES OF Bi12MxO20 ± δ CRYSTALS The piezoelectric, acoustic, optical, chiroptic, photorefractive, and other properties of sillenite-type crystals have been the subject of many reviews, handbooks, and monographs (see, e.g., [1–7, 142–144]). Most published data refer to the well-known compounds BSO, BGO, and BTO. There has been much less work on the properties of Bi12MxO20 ± δ crystals containing Mn+ cations in oxidation states other than 4+. The main physicochemical properties of Bi12MxO20 ± δ (M = Zn, B, Al, Ga, Fe, Tl, Si, Ge, Ti, P, V, [Al, P], [Ga, P], [Fe, P], [Zn, V]) crystals are listed in Table 3, which summarizes our many years of experience in the field. These data supplement and refine the information reported in [145]. The vibrational spectra of the crystals in question were described in detail in [141, 146]; their main spectroscopic characteristics were addressed in several recent studies [80, 147, 148]. CONCLUSIONS In this review, we systematized the large body of information gained over the past four decades about the preparation of Bi12MxO20 ± δ sillenite crystals. We examined the main aspects of the hydrothermal, vaporphase, and melt growth of BSO, BGO, and BTO bulk crystals and single-crystal layers and the conditions for the crystal growth of Bi12MO20 (M = Zn, B, Al, Ga, Fe, Tl, P, V, [Al, P], [Ga, P], [Fe, P], [Zn, V]) by hydrothermal and TSSG processes. We also summarized data on the crystal growth of Bi12MO20 (M = Si, Ge, Ti) doped with Group I–VIII oxides. The problems in the preparation of optically homogeneous sillenite-type single crystals were shown to have their origin in the complex INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 ACKNOWLEDGMENTS This work was supported by the Presidium of the Russian Academy of Sciences (program Controlled Synthesis of Substances with Tailored Properties and Fabrication of Related Functional Materials) and the Bulgarian National Science Foundation (grant no. 1308/2003). REFERENCES 1. Photorefractive Effects and Materials, Nolte, D.D., Ed., Dordrecht: Kluwer, 1995. 2. Buse, K., Light-Induced Charge Transport Processes in Photorefractive Crystals: II. Materials, Appl. Phys. B, 1997, vol. 64, pp. 391–407. 3. Stepanov, S.I., Applications of Photorefractive Crystals, Rep. Prog. Phys., 1994, vol. 57, no. 1, pp. 39–110. 4. Frejlich, J. and Garcia, P.M., Advances in Real-Time Holographic Interferometry for the Measurement of Vibrations and Deformations, Opt. Lasers Eng., 2000, vol. 32, no. 6, pp. 515–527. 5. Blistanov, A.A., Bondarenko, V.S., Chkalova, V.V., et al., Akusticheskie kristally. Spravochnik (Acoustic Crystals: A Handbook), Shaskol’skaya, M.P., Ed., Moscow: Nauka, 1982. 6. Kizel’, V.A. and Burkov, V.I., Girotropiya kristallov (Gyrotropy of Crystals), Moscow: Nauka, 1980. 7. Romashko, R.V., Shandarov, S.M., Kulchin, Yu.N., et al., Reflection Photorefractive Holograms in FiberOptical Interferometer Systems, Pac. Sci. Rev., 2003, vol. 5, pp. 38–41. 8. Mokrushina, E.V., Bryushinin, M.A., Kulikov, V.V., et al., Photoconductive Properties of Photorefractive Sillenites Grown in an Oxygen-Free Atmosphere, J. Opt. Soc. Am. B: Opt. Phys., 1999, vol. 16, pp. 57–62. 9. Karminskii, S.S., Ustroistva obrabotki signalov na ul’trazvukovykh poverkhnostnykh volnakh (Signal Processing Surface Acoustic Wave Devices), Moscow: Sovetskoe Radio, 1975. 10. Yuji Hamasaki, Hideo Gotoh, Masaaki Katoh, and Seiichi Takeuchi, OPSEF: An Optical Sensor for Measurement of High Electric Field Intensity, Electron. Lett., 1980, vol. 16, no. 11, pp. 406–407. 11. Gorchakov, V.K., Kargin, Yu. F., Kutsaenko, V.V., et al., RF Patent 1737371, 1993. 12. Sillen, L.G., X-ray Studies of Bismuth Trioxide, Ark. Kemi. Mineral. Geol. A, 1937, ser. 12, no. 18, pp. 1–15. 13. Skorikov, V.M., Chemistry of Piezoelectric Oxide Compounds, Extended Abstract of Doctoral (Chem.) Disser- S42 2 SKORIKOV et al. tation, Moscow: Kurnakov Inst. of General and Inorganic Chemistry, USSR Acad. Sci., 1985. 14. Kargin, Yu.F., Synthesis, Structure, and Properties of Sillenite-Structure Bismuth Oxide Compounds, Doctoral (Chem.) Dissertation, Moscow: Kurnakov Inst. of General and Inorganic Chemistry, Russ. Acad. Sci., 1998. 15. Abrahams, S.C., Jamieson, P.B., and Bernstein, J.L., Crystal Structure of Piezoelectric Bismuth Germanium Oxide Bi12GeO20, J. Chem. Phys., 1967, vol. 47, pp. 4034–4041. 16. Craig, D.C. and Stephenson, N.C., Structure Studies of Some Body-Centered Cubic Phases of Mixed Oxides Involving Bi2O3: The Structures of Bi25FeO40 and Bi38ZnO60, J. Solid State Chem., 1975, vol. 15, no. 1, pp. 1–8. 17. Abrahams, S.C., Bernstein, J.L., and Svensson, C., Crystal Structure and Absolute Piezoelectric d(14) Coefficient in Laevorotatory Bi12SiO20, J. Chem. Phys., 1979, vol. 72, no. 2, pp. 788–792. 18. Horowitz, H.S., Jacobson, A.J., Newsam, J.M., et al., Solution Synthesis and Characterization of Sillenite Phases, Bi24M2O40 (M = Si, Ge, V, As, P), Solid State Ionics, 1989, vol. 32, pp. 678–690. 19. Radaev, S.F., Simonov, V.I., Kargin, Yu.F., and Skorikov, V.M., New Data on Structure and Crystal Chemistry of Sillenites Bi12MO20, Eur. J. Solid State Inorg. Chem., 1992, vol. 29, pp. 383–392. 20. Radaev, S.F., Tromel, M., Kargin, Yu.F., et al., III III Bi12( Bi 0.50 Tl 0.50 )O19.50, Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1994, vol. 50, pp. 656–659. 21. Delicat, U., Radaev, S.F., Tromel, M., et al., Tetrahedral Coordination of Mn(IV) by Oxygen in Manganese Sillenite Bi12MnO20, J. Solid State Chem., 1994, vol. 110, pp. 66–69. 22. Mary, T.A., Mackay, R., Nguyen, P., and Sleight, A.W., Crystal Structure of Bi12.7Co0.3O19.35, Eur. J. Solid State Inorg Chem., 1996, vol. 33, no. 4, pp. 285–293. 23. Ballman, A.A., The Growth and Properties of Piezoelectric Bismuth Germanium Oxide Bi12GeO20, J. Cryst. Growth, 1967, vol. 1, pp. 37–40. 24. Batog, V.N., Burkov, V.I., Kizel’, V.A., et al., Optical Activity of Bismuth Compounds, Kristallografiya, 1969, vol. 14, no. 5, pp. 928–929. 25. Safonov, A.I., Baryshev, S.A., Nikiforova, T.I., et al., Crystal Growth and Optical Properties of Bi12SiO20, Kristallografiya, 1968, vol. 13, no. 5, pp. 914–915. 26. Safonov, A.I., Baryshev, S.A., Nikiforova, T.I., et al., Crystal Growth and Optical Properties of Bi12GeO20, Kristallografiya, 1969, vol. 14, no. 1, pp. 152–153. 27. Sobolev, A.T., Kopylov, Yu.L., Kravchenko, V.B., and Kucha, V.V., Effect of Growth Conditions on the Optical Homogeneity of Germanium Sillenite Single Crystals, Kristallografiya, 1978, vol. 23, no. 1, pp. 174–179. 28. Kravchenko, V.B., Kucha, V.V., and Sobolev, A.T., Effect of the Interface Shape on the Morphology and Structural Perfection of Czochralski-Grown Gd3Ga5O12 and Bi12GeO20 Crystals, Kristallografiya, 1980, vol. 25, no. 5, pp. 1110–1115. 29. Kukushkin, S.A., Maksikov, A.I., and Petrov, A.A., Impurity Distribution over the Crystal–Melt Interface in Czochralski Growth of Bi12SiO20 Single Crystals, Zh. Tekh. Fiz., 1980, no. 2, pp. 431–433. 30. Voskresenskaya, E.N., Kargin, Yu.F., Skorikov, V.M., and Konstantinov, V.V., Lattice Defects in Single Crystals of Sillenite Compounds, Izv. Akad. Nauk SSSR, Neorg. Mater., 1982, vol. 18, no. 1, pp. 102–106. 31. Kargin, Yu.F., Volkov, V.V., Gospodinov, M., et al., Optical Inhomogeneity of Czochralski-Grown Bi12SiO20 and Bi12GeO20 Single Crystals, Vysokochist. Veshchestva, 1990, no. 5, pp. 67–71. 32. Babonas, G.A., Bondarev, A.D., Leonov, E.I., et al., Absorption Inhomogeneity in Bi12SiO20 Crystals, Zh. Tekh. Fiz., 1981, vol. 51, no. 8, pp. 1701–1702. 33. Picone, P.J., Core Formation in Bi12SiO20, J. Cryst. Growth, 1988, vol. 87, pp. 421–424. 34. Steiner, B., Laor, U., Kuriyama, M., et al., Diffraction Imaging of High Quality Bismuth Silicon Oxide with Monochromatic Synchrotron Radiation: Applications for Crystal Growth, J. Cryst. Growth, 1988, vol. 87, pp. 79–100. 35. Brice, J.C., Bruton, T.M., Hill, O.F., and Whiffin, P.A.C., The Czochralski Growth of Bi12SiO20 Crystals, J. Cryst. Growth, 1974, vol. 24/25, pp. 429–431. 36. Brice, J.C., The Cracking of Czochralski Grown Crystals, J. Cryst. Growth, 1977, vol. 42, no. 1, pp. 427–430. 37. Piekarczyk, W., Swirkowicz, M., and Gazda, S., The Czochralski Growth of Bismuth Germanium Oxide Single Crystals, Mater. Res. Bull., 1978, vol. 13, pp. 889−894. 38. Brice, J.C. and Whiffin, P.A.C., Changes in Fluid Flow during Czochralski Growth, J. Cryst. Growth, 1977, vol. 33, pp. 245–248. 39. Hill, O.F. and Brice, J.C., The Composition of Crystals of Bismuth Silicon Oxide, J. Mater. Sci., 1974, vol. 9, pp. 1252–1254. 40. Whiffin, P.A.C., Brutton, T.M., and Brice, J.C., Simulated Rotational Instabilities in Molten Bismuth Silicon Oxide, J. Cryst. Growth, 1976, vol. 32, pp. 205–210. 41. Tanguay, A.R., Mroczkowski, Jr.S., and Barker, R.C., The Czochralski Growth of Optical Quality Bismuth Silicon Oxide, J. Cryst. Growth, 1977, vol. 42, pp. 431−434. 42. Smet, F. and Van Enckevort, W.J.P., In Situ Microscopic Investigations of Crystal Growth Processes in the System Bi2O3–GeO2, J. Cryst. Growth, 1990, vol. 100, pp. 417–432. 43. Martinez-Lopez, J., Gonzalez-Menas, M., Rojo, J.C., et al., X-ray Topographic Characterization of Growth Defect in Sillenite Type Crystals, Ann. Chim. (Paris, Fr.), 1997, vol. 22, pp. 687–690. 44. Rojo, L.C., Marin, C., Derby, J.J., and Dieguez, E., Heat Transfer and the External Morphology of CzochralskiGrown Sillenite Compounds, J. Cryst. Growth, 1998, vol. 183, pp. 604–613. 45. Jin Wei-qing, The Growth and Melting Morphology of Bi12SiO20 Crystals, Ceram. Int., 1993, vol. 19, pp. 211−214. 46. Gopalakrishnan, R., Krishnamurthy, D., Arivuoli, D., and Ramasamy, P., Microscopy Observations of CzINORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS Grown BSO (Bi12SiO20) Crystals, Mater. Chem. Phys., 1994, vol. 37, no. 1, pp. 90–93. 47. Krishnamurthy, D., Gopalakrishnan, R., Arivuoli, D., and Ramasamy, P., Growth of Oxide Crystals—Effect of Change in Melt Depth, J. Cryst. Growth, 1994, vol. 141, no. 3/4, pp. 371–375. 48. Fontaine, J.P., Extremet, G.P., Chevrier, V., and Launay, J.C., Experimental and Theoretical Treatments of the Czochralski Growth of Bi12SiO20, J. Cryst. Growth, 1994, vol. 139, no. 1/2, pp. 67–80. 49. Aggarwal, M.D., Metzl, R., Wang, W.S., and Choi, J., A Versatile Czochralski Crystal-Growth System with Automatic Diameter Control, Rev. Sci. Instrum., 1995, vol. 66, no. 7, pp. 3939–3942. 50. Gospodinov, M., Tassev, V., and Dimitrov, K., Research of Central Core in Bi12SiO20 Crystals, Cryst. Res. Technol., 1996, vol. 31, no. 5, pp. 595–600. 51. Svestharov, P. and Gospodinov, M.M., The Melt Level Technique of Automatic Czochralski Crystal Growth: Basic Theory and Comparison with the Weighting Method, J. Cryst. Growth, 1992, vol. 118, no. 3/4, pp. 439– 451. 52. Santos, M.T., Marin, C., and Dieguez, E., Morphology of Bi12GeO20 Crystals Grown along the (111) Directions by the Czochralski Method, J. Cryst. Growth, 1996, vol. 160, no. 3/4, pp. 283–288. 53. Wada, N. and Morinaga, K., T–T–T Diagrams and C– C–C Diagrams for Growth of Sillenite Single-Crystals, J. Ceram. Soc. Jpn., 1998, vol. 106, no. 6, pp. 576–581. 54. Takeda, S., Sugiyama, K., and Waseda, Y., StructuralAnalysis of Molten Bismuth-Germanate Compounds, Jpn. J. Appl. Phys., 1993, vol. 32, no. 12, pp. 5633−5636. 55. Fu, S. and Ozoe, H., Solidification Characteristics of Metastable δ-Bi12SiO20 and Stable γ-Bi12SiO20, J. Phys. D: Appl. Phys., 1996, vol. 29, no. 7, pp. 2032–2043. 56. Fu, S. and Ozoe, H., Metastable Delta-Bi12SiO20 and Its Effect on the Quality of Grown Single-Crystals of Gamma-Bi12SiO20, J. Mater. Res., 1996, vol. 11, no. 10, pp. 2575–2582. 57. Santos, M.T., Rojo, J.C., Cintas, A., et al., Changes in the Solid–Liquid Interface during Growth of Bi12SiO20, Bi12GeO20, and LiNbO3 Crystals Grown by the Czochralski Method, J. Cryst. Growth, 1995, vol. 156, pp. 413–420. 58. Budenkova, O.N., Vasiliev, M.G., Yuferev, V.S., et al., Simulation of Global Heat Transfer in the Czochralski Process for BGO Sillenite Crystals, J. Cryst. Growth, 2004, vol. 266, nos. 1–3, pp. 103–108. 59. Aggarwal, M.D., Wang, W.S., Choi, J., et al., Morphology and Formation of the Color Core of Bi12SiO20 Crystals Grown by Czochralski Method, J. Cryst. Growth, 1994, vol. 137, pp. 132–135. 60. Rojo, J.C., Dieguez, E., and Derby, J.J., A Heat Shield to Control Thermal Gradients, Melt Convection, and Interface Shape during Shouldering in Czochralski Oxide Growth, J. Cryst. Growth, 1999, vol. 200, pp. 329–334. 61. Babu, S., Kitamura, K., Takekawa, S., et al., Interband Transitions in Bismuth Germanate Crystals Grown INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 S43 from the Melts of Several [Ge]/[Bi] Ratios, J. Opt. Soc. Am. B: Opt. Phys., 1999, vol. 16, no. 8, pp. 1243–1249. 62. Kumaragurubaran, S., Babu, S.M., Kitamura, K., et al., Defect Analysis in Czochralski Grown Bi12SiO20 Crystals, J. Cryst. Growth, 2001, vol. 229, nos. 1–4, pp. 233–237. 63. Xu Xuewu, Liao Jingying, Shen Bingfu, et al., Bi12SiO20 Single Crystal Growth by the Bridgman Method, J. Cryst. Growth, 1993, vol. 133, pp. 267–272. 64. Xu Xuewu, Liao Jingying, Shen Bingfu, et al., Vertical Bridgman Growth and Optical Properties of Doped Bi12SiO20 Crystals, Cryst. Res. Technol., 1994, vol. 29, no. 2, pp. 207–213. 65. Tananaev, I.V., Skorikov, V.M., Kutvitskii, V.A., and Voskresenskaya, E.N., Platinum Solubility in Bi2O3– ExOy (E = Si, Ti, Ge, Zn, Cd) Melts, Izv. Akad. Nauk SSSR, Neorg. Mater., 1981, vol. 17, no. 4, pp. 663–668. 66. Bruton, T.M., Brice, J.C., Hill, O.F., and Whiffin, P.A.C., The Flux Growth of Some γ-Bi2O3 Crystals by the Top-Seeded Technique, J. Cryst. Growth, 1974, vol. 23, pp. 21–24. 67. Bruton, T.M., Hill, O.F., Whiffin, P.A.C., and Brice, J.C., The Growth of Some Gamma Bismuth Oxide Crystals, J. Cryst. Growth, 1976, vol. 32, pp. 27–28. 68. Volkov, V.V., Crystal Growth and Physicochemical Characterization of Bismuth Titanate, Cand. Sci. (Chem.) Dissertation, Moscow: Kurnakov Inst. of General and Inorganic Chemistry, USSR Acad. Sci., 1988. 69. Prokofiev, V.V., Carvalho, J.F., Andreeta, J.P., et al., Growth and Characterization of Photorefractive Bi12TiO20 Single-Crystals, Cryst. Res. Technol., 1995, vol. 30, no. 2, pp. 171–176. 70. Gospodinov, M., Marinova, V., Sainov, V., and Sveshtarov, P., The Growth and Optical Properties of Doped Bismuth Titanate, Mater. Res. Bull., 1993, vol. 28, no. 3, pp. 445–449. 71. Mersch, F., Buse, K., Sauf, W., et al., Growth and Characterization of Undoped and Doped Bi12TiO20 Crystals, Phys. Status Solidi A, 1993, vol. 140, pp. 273–281. 72. Miyazawa, S. and Tabata, T., Bi2O3–TiO2 Binary Phase Diagram Study for TSSG Pulling of Bi12TiO20 Single Crystals, J. Cryst. Growth, 1998, vol. 191, pp. 512–516. 73. Egorysheva, A.V., Burkov, V.I., Kargin, Yu.F., and Skorikov, V.M., Stoichiometric Dependence of Optical and Photoconductive Properties of Bi12TiO20 Single Crystals, Proc. SPIE–Int. Soc. Opt. Eng., 2001, vol. 4358, pp. 97–101. 74. Kargin, Yu.F., Egorysheva, A.V., Volkov, V.V., et al., Growth and Characterization of Doped Bi12TiO20 Single Crystals, 14th Int. Conf. on Crystal Growth, ICCG14, Grenoble, 2004, p. 306. 75. Carvalho, J.F. and Hernandes, A.C., Large Bi12TiO20 Single Crystals: A Study of Intrinsic Defects and Growth Parameters, J. Cryst. Growth, 1999, vol. 205, pp. 185–190. 76. Burianek, M. and Muhlberg, M., Crystal Growth of Boron Sillenite Bi24B2O39, Cryst. Res. Technol., 1997, vol. 32, no. 8, pp. 1023–1027. S44 SKORIKOV et al. 77. Egorysheva, A.V., Volkov, V.V., Burkov, V.I., et al., Growth and Characterization of Bismuth Borate Crystals, Opt. Mater., 1999, vol. 13, pp. 361–365. 78. Burianek, M., Held, P., and Muehlberg, M., Improved Single Crystal Growth of the Boron Sillenite “Bi24B2O39” and Investigation of the Crystal Structure, Cryst. Res. Technol., 2002, vol. 37, no. 8, pp. 785–796. 79. Volkov, V.V., Egorysheva, A.V., and Skorikov, V.M., Growth and Some Physical Properties of Sillenite-Type Phases with Orientational Disorder, Neorg. Mater., 1993, vol. 29, no. 5, pp. 652–655 [Inorg. Mater. (Engl. Transl.), vol. 29, no. 5, pp. 560–563]. 80. Kargin, Yu.F., Egorysheva, A.V., Volkov, V.V., and Skorikov, V.M., Sillenites Single Crystals of Different Composition: Crystal Growth from the Melt and Characterization, 14th Int. Conf. on Crystal Growth, ICCG14, Grenoble, 2004, p. 448. 81. Ballman, A.A., Brown, H., Tien, P.K., and Martin, R.J., The Growth of Single Crystalline Waveguiding Thin Films of Piezoelectric Sillenites, J. Cryst. Growth, 1973, vol. 20, pp. 251–255. 82. Tada, K., Kuhara, Y., Tatsumi, M., and Yamaguchi, T., Liquid-Phase Epitaxial Growth of Bismuth Silicon Oxide Single-Crystal Film: A New Optically Activated Optical Switch, Appl. Opt., 1982, vol. 21, no. 16, pp. 2953–2959. 83. Kargin, Yu.F., Salikaev, Yu.R., Shandarov, S.M., and Tsisar’, I.V., Two-Beam Coupling in Index Gratings in a Planar Bi12TiO20/Bi12GeO20 Waveguide, Pis’ma Zh. Tekh. Fiz., 1994, vol. 20, no. 24, pp. 55–58. 84. Bondarev, A.D., Katsavets, N.I., Kudrik, I.E., et al., Growth and Optical and Photoelectric Properties of Heteroepitaxial Bismuth Titanate and Bismuth Gallate Films, Pis’ma Zh. Tekh. Fiz., 1985, vol. 11, no. 12, pp. 713–717. 85. Kukushkin, S.A., Razumov, S.V., Kalinkin, I.P., and Krasin’kova, N.V., Liquid-Phase Growth of Thin Bi12TixSi1 – xO20 Films, Kristallografiya, 1990, vol. 35, no. 6, pp. 1517–1522. 86. Roszko, M., Skulska, E., Chojnacka, I., et al., Studies on Preparing a Planar Waveguide in the Bi12GeO20 Crystal, Pr. Inst. Fiz., Politech. Warsz., 1986, no. 31/32, pp. 101–112. 87. Kargin, Yu.F., Egorysheva, A.V., Volkov, V.V., et al., The Growth of Photorefractive Planar BTO/BSO and BTO/BGO Waveguide, 14th Int. Conf. on Crystal Growth, ICCG-14, Grenoble, 2004, p. 395. 88. Ivleva, L.I. and Kuz’minov, Yu.S., Melt Growth of Single-Crystal Ca(VO4)2 and Bi12SiO20 Plates by the Stepanov Method, Izv. Akad. Nauk SSSR, Ser. Fiz., 1983, vol. 47, no. 2, pp. 395–398. 89. Ivleva, L.I., Kuz’minov, Yu.S., Osiko, V.V., and Polozkov, N.M., The Growth of Multicomponent Oxide Single Crystals by Stepanov’s Technique, J. Cryst. Growth, 1987, vol. 82, no. 1/2, pp. 168–176. 90. Miyamoto, K., Miyamoto, H., and Komoda, Sh., Growth of Thin Plates of Bi12SiO20 Single Crystals, Mater. Res. Bull., 1980, vol. 15, pp. 729–734. 91. Mitsuyu, T., Wasa, K., and Hayakawa, S., RF-Sputtered Epitaxial Films of Bi12TiO20 on Bi12GeO20 for Optical Waveguiding, J. Cryst. Growth, 1977, vol. 41, pp. 151−156. 92. Baglikov, V.B., Dmitriev, V.A., Kornetov, V.N., et al., Crystal Structure and Electrophysical Properties of Bismuth–Germanate Films, Izv. Akad. Nauk SSSR, Neorg. Mater., 1985, vol. 21, no. 5, pp. 719–724. 93. Nomura, K. and Ogawa, H., Electro-optic Effects of Electron Cyclotron Resonance Plasma-Sputtered Bi12SiO20 Thin Film on Sapphire, J. Appl. Phys., 1991, vol. 70, pp. 3234–3238. 94. Youden, K.E., Eason, R.W., and Gover, M.C., Investigation of Photorefractive Wave-Guides Fabricated by Excimer Laser Ablation and Ion-Implantation, in Photorefractive Materials, Effects, and Devices, Beverly, 1991, pp. 460–463. 95. Youden, K.E., Eason, R.W., Gover, M.C., and Vainos, N.A., Epitaxial Growth of Bi12GeO20 ThinFilm Waveguides Using Excimer Laser Ablation, Appl. Phys. Lett., 1991, vol. 59, pp. 1929–1931. 96. Alfonso, J., Martin, M., Mendiola, J., et al., Bi12(GaBi1 – x)O19.5 Optical Waveguides Grown by Pulsed Laser Deposition, J. Appl. Phys., 1996, vol. 79, no. 11. 97. Alfonso, J., Volkov, V.V., Martin, M., et al., Photoconductive Bi12MO20-Type Films Prepared by Pulsed Laser Deposition, J. Mater. Res., 1999, vol. 14, no. 11, pp. 4409–4417. 98. Silvestri, V.J., Sedwick, T.O., and Landermann, J.B., Vapor Growth of Bi12GeO20, Bi2O3, and BiOCl, J. Cryst. Growth, 1973, vol. 20, pp. 165–168. 99. Nagao, Y. and Mimura, Y., Growth and Characterization of Bi12SiO20 Films by Metalorganic Chemical Vapor Decomposition, IEEE J. Quantum Electron., 1987, vol. 23, pp. 2152–2158. 100. Plyaka, S.N., Sokolyanskii, G.Ch., Klebanskii, E.O., and Sadovskaya, L.Ja., Conductivity of the Bi12SiO20 Thin Films, Condens. Mater. Phys., 1999, vol. 2, no. 4, pp. 625–630. 101. Prokofiev, V.V., Andreeta, J.P., de Lima, C.J., et al., Growth of Single-Crystal Photorefractive Fibers of Bi12SiO20 and Bi12TiO20 by the Laser-Heated Pedestal Growth Method, J. Cryst. Growth, 1994, vol. 137, pp. 528–534. 102. Prokofiev, V.V., Kamshilin, A.A., and Jaaskelainen, T., Progress in the Synthesis of Photorefractive Sillenite Structure Materials, Proc. SPIE–Int. Soc. Opt. Eng., 1996, vol. 3178, pp. 14–21. 103. Fu, S. and Ozoe, H., Enhancement of Growth-Rate for BSO Crystals by Improving Thermal Conditions, Mater. Res. Bull., 1996, vol. 31, no. 11, pp. 1341–1354. 104. Quon, D.H.H., Chehab, S., Aota, J., et al., Float-Zone Crystal Growth of Bismuth Germanate and Numerical Simulation, J. Cryst. Growth, 1993, vol. 134, pp. 266−274. 105. Fu, S. and Ozoe, H., Solid Phase Reaction in Synthesis of Bi12SiO20 Source-Rods for Single Crystal Growth in a Floating Zone, J. Phys. Chem. Solids, 1996, vol. 57, no. 9, pp. 1269–1278. 106. Saghir, M.Z., Islam, M.R., Maffei, N., and Quon, D.H.H., Three-Dimensional Modeling of Bi12GeO20 Using the INORGANIC MATERIALS Vol. 41 Suppl. 1 2005 GROWTH OF SILLENITE-STRUCTURE SINGLE CRYSTALS Float Zone Technique, J. Cryst. Growth, 1998, vol. 193, pp. 623–635. 107. Maffei, N., Quon, D.H.H., Aota, J., et al., Characterization of Bi12GeO20 Processed in a Microgravity Environment, J. Cryst. Growth, 1997, vol. 181, no. 4, pp. 382−389. 108. Litvin, B.N., Shaldin, Yu.V., and Pitovranova, I.E., Crystal Growth and Electro-optic Properties of Silicon Sillenite, Kristallografiya, 1968, vol. 13, no. 6, pp. 1106–1108. 109. Surnina, V.S. and Litvin, B.N., Crystallization in the Systems Na2O–Bi2O3–SiO2–H2O and Na2O–Bi2O3– GeO2–H2O, Izv. Akad. Nauk SSSR, Neorg. Mater., 1970, vol. 6, no. 9, pp. 1695–1697. 110. Surnina, V.S. and Litvin, B.N., Hydrothermal Crystallization in the Systems Na2O–MeO2–Bi2O3–H2O (Me = Al, Ga, In), Kristallografiya, 1970, vol. 15, no. 3, pp. 604–607. 111. Kurazhkovskaya, V.S. and Litvin, B.N., Crystallization in the Na2O–Bi2O3–Fe2O3–H2O System, Izv. Akad. Nauk SSSR, Neorg. Mater., 1973, vol. 9, no. 4, pp. 652−654. 112. Kurazhkovskaya, V.S., Hydrothermal Synthesis and Properties of Bismuth Oxide Compounds, Extended Abstract of Cand. Sci. (Geol.–Mineral.) Dissertation, Moscow: Moscow State Univ., 1971. 113. Kurazhkovskaya, V.S., Hydrothermal Crystallization of Phosphorus Sillenite, Kristallografiya, 1976, vol. 21, no. 6, pp. 1240–1242. 114. Barsukova, M.L., Kuznetsov, V.A., Lobachev, A.N., and Shaldin, Yu.V., Hydrothermal Growth of Bismuth Titanates, J. Cryst. Growth, 1972, vol. 13/14, pp. 530−534. 115. Mar’in, A.A., Synthesis and Seeded Crystal Growth of Sillenites under Hydrothermal Conditions, Extended Abstract of Cand. Sci. (Geol.–Mineral.) Dissertation, Moscow: Moscow State Univ., 1980. 116. Samoilovich, L.A., Solubility of Silicon Sillenite in Alkaline Hydrothermal Solutions, in Sintez monokristallicheskogo mineral’nogo syr’ya (Synthesis of Single-Crystal Mineral Raw Materials), Moscow: Nedra, 1982, pp. 49–53. 117. Yudin, A.N., Kaplunnik, L.N., Mar’in, A.A., et al., Xray Measurements on Hydrothermal Crystals and Epitaxial Films with the Sillenite Structure, Izv. Akad. Nauk SSSR, Neorg. Mater., 1989, vol. 25, no. 2, pp. 267–270. 118. Yudin, A.N., Hydrothermal Crystal Growth and Morphology of Sillenites, Cand. Sci. (Geol.–Mineral.) Dissertation, Moscow: Moscow State Univ., 1987. 119. Barsukova, M.L., Kuznetsov, V.A., Lobachev, A.N., and Tanakina, T.N., Crystallization of Bismuth Titanates, Kristallografiya, 1972, vol. 17, no. 4, pp. 846–850. 120. Yudin, A.N., Mar’in, A.A., and Balitskii, V.S., Morphology of Hydrothermally Grown Sillenite-Structure Crystals, Kristallografiya, 1985, vol. 31, no. 5, pp. 1039–1040. 121. Larkin, J., Harris, M., and Cormier, J.E., Hydrothermal Growth of Bismuth Silicate (BSO), J. Cryst. Growth, 1993, vol. 128, pp. 871–875. 122. Harris, M., Larkin, J., Cormier, J.E., and Armington, A.F., Optical Studies of Czochralski and Hydrothermal BisINORGANIC MATERIALS Vol. 41 Suppl. 1 2005 S45 muth Silicate, J. Cryst. Growth, 1994, vol. 137, pp. 128–131. 123. Leigh, W.B., Larkin, J.J., Harris, M.T., and Brown, R.N., Characterization of Czochralski- and HydrothermalGrown Bi12SiO20, J. Appl. Phys., 1994, vol. 76, no. 2, pp. 660–666. 124. Safronov, G.A., Speranskaya, E.I., Batog, V.N., et al., Bi2O3–Ga2O3 Phase Diagram, Zh. Neorg. Khim., 1971, vol. 16, no. 2, pp. 526–529. 125. Dzhalaladdinov, F.F., Phase Relations in the Ternary Systems Bi2O3–ZnO–EO2 and Bi2O3–Ga2O3–EO2, E = Si and Ge, Cand. Sci. (Chem.) Dissertation, Moscow: Kurnakov Inst. of General and Inorganic Chemistry, USSR Acad. Sci., 1984. 126. Speranskaya, E.I., Skorikov, V.M., Terekhova, V.A., and Rode, E.Ya., Bi2O3–Fe2O3 Phase Diagram, Izv. Akad. Nauk SSSR, Ser. Khim., 1965, no. 5, pp. 905–906. 127. Kargin, Yu.F. and Egorysheva, A.V., Synthesis and Structure of the Bi24B2O39 Sillenite, Neorg. Mater., 1998, vol. 34, no. 7, pp. 859–863 [Inorg. Mater. (Engl. Transl.), vol. 34, no. 7, pp. 714–718]. 128. Takagi, K., Pukazawa, F., and Ishii, M., Inversion of the Direction of the Solid–Liquid Interface on the Czochralski Growth of GGG Crystals, J. Cryst. Growth, 1976, vol. 32, p. 89. 129. Zhereb, V.P. and Skorikov, V.M., Metastable States in Bismuth-Containing Oxide Systems, Inorg. Mater., 2003, vol. 39, suppl. 2, pp. S121–S145. 130. Kargin, Yu.F., Mar’in, A.A., Vasil’ev, A.Ya., et al., Growth of Enantiomorphous Sillenite-Structure Crystals, Izv. Akad. Nauk SSSR, Neorg. Mater., 1981, vol. 17, no. 8, pp. 1428–1429. 131. Chernov, M.A., Degtyarev, Yu.L., Petrashen’, P.V., et al., X-ray Topographic Characterization of SilleniteStructure Single Crystals, Izv. Akad. Nauk SSSR, Neorg. Mater., 1986, vol. 22, no. 5, pp. 798–800. 132. Milenov, T.I., Rafailov, P.M., Botev, P.A., and Gospodinov, M.M., X-ray Diffraction Topography Investigation of the Core in Bi12SiO20 Crystals, Mater. Res. Bull., 2002, vol. 37, no. 9, pp. 1651–1658. 133. Milenov, T.I., Botev, P.A., Rafailov, P.M., and Gospodinov, M.M., X-ray Diffraction Topography Observations of the Core in Bi12SiO20 Crystal Doped with Mn, J. Mater. Sci. Eng. B, 2004, vol. 106, pp. 148–154. 134. Tarasova, L.S., Surface Dissolution of Sillenite- and Eulytite-Structure Bismuth Germanate and Silicate Single Crystals, Cand. Sci. (Chem.) Dissertation, Moscow: Kurnakov Inst. of General and Inorganic Chemistry, USSR Acad. Sci., 1985. 135. Lin, C. and Witt, A.F., Decoration of Dislocations in Bi12SiO20 Crystals by Annealing in a Reducing Atmosphere, J. Cryst. Growth, 1994, vol. 140, pp. 444–446. 136. Gavrilov, V.A., Development and Implementation of Optical Techniques for Characterization of Inhomogeneities in Sillenite-Structure Single Crystals, Cand. Sci. (Eng.) Dissertation, Moscow: Moscow Inst. of Steel and Alloys, 1986. 137. Grabmaier, B.C. and Oberschmid, R., Properties of Pure and Doped Bi12GeO20 and Bi12SiO20 Crystals, Phys. Status Solidi A, 1986, vol. 96, pp. 199–210. S46 SKORIKOV et al. 138. Maida, S., Higuchi, M., and Kodaira, K., Growth of Bi12SiO20 Single Crystals by the Pulling-down Method with Continuous Feeding, J. Cryst. Growth, 1999, vol. 205, no. 3, pp. 317–322. 139. Lan, C.W., Chen, H.J., and Tsai, C.B., Zone-Melting Czochralski Pulling Growth of Bi12SiO20 Single Crystals, J. Cryst. Growth, 2002, vol. 245, no. 1/2, pp. 56−62. 140. Egorysheva, A.V., Burkov, V.I., Kargin, Yu.F., et al., Optical Properties of Bi25TlO39 and Bi25GaO39 Single Crystals, Neorg. Mater., 1999, vol. 35, no. 7, pp. 840−844 [Inorg. Mater. (Engl. Transl.), vol. 35, no.7, pp. 709–712]. 141. Burkov, V.I., Gorelik, V.S., Egorysheva, A.V., and Kargin, Yu.F., Laser Raman Spectroscopy of Crystals with the Structure of Sillenite, J. Russ. Laser Res., 2001, vol. 22, no. 3, pp. 243–267. 142. Burkov, V.I., Egorysheva, A.V., and Kargin, Yu.F., Optical and Chiro-optical Properties of Crystals with Sillenite Structure, Kristallografiya, 2001, vol. 46, no. 2, pp. 312–335. 143. Arizmendi, L., Cabrera, J.M., and Agullo-Lopez, F., Material Properties and Photorefractive Behaviour of BSO Family Crystals, Int. J. Opt., 1992, vol. 7, no. 2, pp. 149–180. 144. Petrov, M.P., Stepanov, S.I., and Khomenko, A.V., Fotorefraktivnye kristally v kogerentnoi optike (Photorefractive Crystals in Coherent Optics), St. Petersburg: Nauka, 1992. 145. Kargin, Yu.F. and Skorikov, V.M., Photorefractive Crystals of the Sillenite Structure, Ferroelectrics, 1995, vol. 167, pp. 257–265. 146. Egorysheva, A.V., Burkov, V.I., Kargin, Yu.F., et al., Atomic Structure Features of Sillenite Crystals as Probed by Raman Spectroscopy, Zh. Neorg. Khim., 2005, vol. 50, no. 2, pp. 238–245. 147. Egorysheva, A.V., Absorption Edge of Bi12MxO20 ± δ Sillenite Crystals (M = Zn, B, Ga, P, V, [Al, P], [Ga, P], [Fe, P], [Zn, V]), Zh. Neorg. Khim., 2005, vol. 50, no. 3, pp. 461–466. 148. Egorysheva, A.V., Burkov, V.I., Kargin, Yu.F., and Makhov, V.N., Reflection Spectra of Bi12MxO20 ± δ (M = Zn, Ga, Fe, [Ga, P], [Fe, P], [Zn, V]) Sillenite Crystals, Zh. Neorg. Khim., 2005, vol. 50, no. 7, pp. 1044–1049. SPELL: 1. levorotatory, 2. Laevorotatory (Ref.), Behaviour (Ref. 143)—? INORGANIC MATERIALS Vol. 41 Suppl. 1 2005

RELATED PAPERS

RELATED TOPICS

Log In

Growth of sillenite-structure single crystals

Growth of sillenite-structure single crystals

Related Papers

RELATED PAPERS

RELATED TOPICS