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The Na3Nd(BO3)2-NdBO3 phase diagram was investigated by the solid-state synthesis and DSC methods. Na3Nd(BO3)2, Na3Nd2(BO3)3 and NdBO3 were grown by spontaneous crystallization from the Na2O-B2O3-NaF flux. Typical Nd3+ luminescence of 4F3/2 → 4I9/2 and 4F3/2 → 4I11/2 electron transitions at 875 nm and 1054 nm were registered. Maximum integral intensity of the luminescence was observed for Na3Nd2(BO3)3 crystals, more than twice that of NdBO3, Na3Nd(BO3)2. [ABSTRACT FROM AUTHOR]

A novel method of crystal growth by introducing jet flow to the pyramidal‐restriction long‐seed growth system of potassium dihydrogen phosphate (KH2PO4, KDP) in rotating crystal method, namely, the jet‐rotating crystal method, is proposed. To evaluate the prospect of this new method, three‐dimensional (3D) time‐dependent numerical simulations of flow and mass transfer involved in the jet‐rotating crystal method are conducted. Compared with the rotating crystal method, the jet‐rotating crystal method can improve the magnitude and distribution homogeneity of the prismatic face supersaturation and obtain high‐quality KDP crystals. The supersaturation on the prismatic face as a function of rotation rate, jet velocity, and crystal size is investigated. The effects of solution flow on mass transfer are analyzed in detail. A further improvement in the magnitude and distribution homogeneity of the prismatic face supersaturation can be observed through designing the jet flow pipes to swing periodically in vertical plane. Besides, the role of natural and forced convection in mass transport is discussed, which indicates that the effects of natural convection can be neglected when the jet velocity is equal to or greater than 0.6 m s–1. [ABSTRACT FROM AUTHOR]

Managing a crystallization process adequately, it is possible to obtain a crystalline product having the desired crystal size distribution. Recommendations for selecting crystallization parameters that are needed to achieve this goal are given basing of a theoretical analysis in which special attention is paid to the growth of crystals from solutions with a preset concentration. Mathematical equations which enable calculation of the theoretical yield for the crystallization process have been elaborated. New formula giving the crystal nuclei number per unit volume as a function of both supersaturation and nucleation time has been devised based on the logistic kinetics of crystal nucleation proceeding under constant supersaturation. The quantitative relation between number density and mean size of crystals growing in batch crystallization is calculated. The calculation shows that the mean size of crystals reached at any time of their growth is inversely proportional to root third of the crystal number density. [ABSTRACT FROM AUTHOR]

K2NiXCo(1−X) (SO4)2·6H2O (KCNSH) mixed crystal is a promising material for solar blind optical filters, combining high transparency in the ultraviolet range with effective suppression of the visible spectral region. Increasing the mechanical strength of these crystals is important to enable them to be machined in the manufacture of optical elements. A comprehensive study of the inhomogeneities and crack resistance of KCNSH crystal as a function of the growth conditions was carried out. The influence of the radial and mosaic inhomogeneity, as well as other structural defects, on the crack resistance of the crystals was analyzed. To assess the crack resistance of crystals, the parameters ca (crack length), c/a (the ratio of crack length to the size of the indentation), and KC (fracture toughness) were used. The correctness of the obtained results was analyzed. The conditions for growing KCNSH crystals with the best crack resistance were determined on the basis of the results of the study. It is shown that growing the mixed crystals using the temperature difference technique with a peripheral solution supply into the shaper provides the best crystal quality.

The mosaic and radial inhomogeneity of shaped mixed crystals of K2NixCo(1–x)(SO4)2·6H2O (KCNSH) were studied depending on the supercooling of solution, its velocity and its method of supply into the shaper. It was shown that mosaic inhomogeneity could be suppressed when solution is supercooled to about 2 °C. Peripheral supply of the solution (tangential to the wall of the shaper to create a “swirling” flow) with a rate of 55–135 cm/s provides better composition uniformity along the crystal surface in comparison with upright supply of the solution (flow is perpendicular to the crystal surface).

Cs2AgBiBr6 high purity polycrystalline powders are synthesized by solution method. The millimeter‐sized Cs2AgBiBr6 crystals are obtained by cooling method with hydrobromic acid as solvent. Powder X‐Ray diffraction (XRD) analysis shows that the crystal is of cubic structure and its lattice constant is a=b=c=11.2562 Å. Optical absorption property is tested by ultraviolet‐visible (UV‐Vis) spectrophotometer. The results show that the absorption edge of the Cs2AgBiBr6 crystal is at about 593 nm and the band gap value is 2.12 eV. In addition, the thermogravimetric analysis/differential thermal analysis (TG/DTA) curves of Cs2AgBiBr6 crystal at 20–800 °C are measured. The thermal decomposition mechanism of Cs2AgBiBr6 crystal is analyzed. The results show that Cs2AgBiBr6 crystal with high quality can be prepared by solution method, and it has potential application advantages in the field of photoelectric devices. [ABSTRACT FROM AUTHOR]

This review, for the first time, summarizes the results of studies of the defect formation mechanisms in mixed crystals grown from aqueous solutions. The general mechanism of interaction of a crystal with a foreign solution is described (reaction of isomorphous replacement). As a result of this reaction, the crystal surface turns into a mosaic of local areas where multidirectional processes (dissolution and growth) occur simultaneously. Data on mosaic microinhomogeneity, which is a new type of composition inhomogeneity inherent solely to multicomponent crystals, is presented. A new mechanism for the mismatch stress relaxation in heterocompositions of brittle crystals grown from low-temperature solutions is described; in this case, the formation of misfit dislocations is impossible and stress relaxation occurs due to the formation of numerous inclusions at the interface. The general concept of growing high-quality mixed crystals from solutions is described, using the example of K2(Co, Ni)(SO)2 · 6H2O (KCNSH) mixed crystals.

In this work, large-sized CH3NH3PbBr3 single crystals were successful grown using solution evaporation method with hydrohalic acid and N, N-Dimethylformamide (DMF) as solvent respectively. The lattice parameters of cubic CH3NH3PbBr3 were estimated using XRD method. The solubility of CH3NH3PbBr3 in hydrobromic acid was determined at the temperature range between 20 °C-90 °C. A special micro-solution crystallizer was designed to in-situ study the morphology of CH3NH3PbBr3 crystal. The largest crystal face was indexed by the XRD patterns and it would be {110} for CH3NH3PbBr3 grown from HBr solution and {100} from DMF solution. The results show that solvent would affect the morphology and crystal habit greatly during crystal growth from solution. [ABSTRACT FROM AUTHOR]

Single crystals of Lithium Hydrogen phthalate dihydrate (LHP), a semi-organic nonlinear optical material have been successfully grown from aqueous solution, by slow evaporation solution growth technique. Single crystals in size 40×10× 5 mm 3 were grown in a period of 2 weeks. The grown crystals were characterized by single crystal X-ray diffraction. LHP crystallizes in Pnm space group of Orthorhombic system, with the unit-cell dimensions at 293(2) K; a = 16.8356(10) Å; b = 6.8187(5) Å; c = 8.1967(6) Å; α = 90°, β = 90°, γ = 90°. Third order non-liner studies have also been studied by Z-scan techniques. Nonlinear absorption and nonlinear refractive index were found out and the third order bulk susceptibility of compound was also estimated. [ABSTRACT FROM AUTHOR]

Abstract: A semiorganic non-linear optical single crystal of glycine sodium nitrate has been grown from aqueous solution by unidirectional crystal growth method. The phase of the grown crystal was identified using single crystal X-ray analysis. The functional groups present in the crystal were identified using FTIR analysis. Optical absorption studies have confirmed that the grown crystal possess less absorption in the entire visible region. A stable broad peak in the violet region was observed in the emission spectrum. Thermal stability and melting temperature of the as grown crystal was identified from TG-DTA analysis. The mechanical strength and the work hardening co-efficient were determined from Vicker''s microhardness measurements for different loads. Dielectric behaviour of the grown crystal was studied and the results are discussed in detail. [Copyright &y& Elsevier]

Abstract: Single crystals of semicarbazone of p-hydroxy-3-methoxy acetophenone (SPH3MA) were grown by a slow evaporation solution growth technique at room temperature. This is the first report in the literature on the crystallization of SPH3MA. The cell parameters of the grown crystals were estimated by single crystal X-ray diffraction analysis. The various planes of reflection were identified from the XRD powder pattern. The presence of functional groups was identified from FTIR and 1H NMR. The results were found to be in accordance with the structure of the crystal. The formation of charge transfer complex was confirmed by UV–vis–NIR spectroscopy. The thermal stability of the grown crystal was studied by thermal analysis. [ABSTRACT FROM AUTHOR]

Abstract: Ferroelectric triglycine sulfate (TGS) single crystals have been grown by a temperature-lowering technique from the aqueous solution by doping with samarium sulfate, ytterbium sulfate and terbium sulfate in the ferroelectric phase. The effects of these different dopants on the morphology, growth and various properties such as dielectric, pyroelectric and piezoelectric of doped TGS crystals have been investigated. The decrease in values of dielectric constant and pyroelectric coefficient is observed while the dielectric loss has increased. Using these parameters, figure-of-merits for their use in infrared sensors have also been reported and compared with pure TGS crystal. The Vickers''s hardness of doped TGS crystals along (010) crystallographic face has increased. [Copyright &y& Elsevier]

An aqueous solution technique has been developed for the growth of TGS-related mixed crystals, and particularly applied to TGS x ·TGSe 1- x ones. The key point of this technique is that temperature is kept constant during the whole process. Due to the different solubility curves of the two implied species, growth methods based on slow cooling of saturated solution are expected to yield crystals with uncertain composition and homogeneity. Our method is based on the slow evaporation of the solvent (water) at a given temperature. The evaporation rate is controlled by a regulated warmed dry air flow over the solution surface. Measurements of T c vs. x of selected samples are reported. [ABSTRACT FROM AUTHOR]

K2NiXCo(1−X) (SO4)2·6H2O (KCNSH) mixed crystal is a promising material for solar blind optical filters, combining high transparency in the ultraviolet range with effective suppression of the visible spectral region. Increasing the mechanical strength of these crystals is important to enable them to be machined in the manufacture of optical elements. A comprehensive study of the inhomogeneities and crack resistance of KCNSH crystal as a function of the growth conditions was carried out. The influence of the radial and mosaic inhomogeneity, as well as other structural defects, on the crack resistance of the crystals was analyzed. To assess the crack resistance of crystals, the parameters ca (crack length), c/a (the ratio of crack length to the size of the indentation), and KC (fracture toughness) were used. The correctness of the obtained results was analyzed. The conditions for growing KCNSH crystals with the best crack resistance were determined on the basis of the results of the study. It is shown that growing the mixed crystals using the temperature difference technique with a peripheral solution supply into the shaper provides the best crystal quality. [ABSTRACT FROM AUTHOR]

The mosaic and radial inhomogeneity of shaped mixed crystals of K2NixCo(1–x)(SO4)2·6H2O (KCNSH) were studied depending on the supercooling of solution, its velocity and its method of supply into the shaper. It was shown that mosaic inhomogeneity could be suppressed when solution is supercooled to about 2 °C. Peripheral supply of the solution (tangential to the wall of the shaper to create a "swirling" flow) with a rate of 55–135 cm/s provides better composition uniformity along the crystal surface in comparison with upright supply of the solution (flow is perpendicular to the crystal surface). [ABSTRACT FROM AUTHOR]

This review, for the first time, summarizes the results of studies of the defect formation mechanisms in mixed crystals grown from aqueous solutions. The general mechanism of interaction of a crystal with a foreign solution is described (reaction of isomorphous replacement). As a result of this reaction, the crystal surface turns into a mosaic of local areas where multidirectional processes (dissolution and growth) occur simultaneously. Data on mosaic microinhomogeneity, which is a new type of composition inhomogeneity inherent solely to multicomponent crystals, is presented. A new mechanism for the mismatch stress relaxation in heterocompositions of brittle crystals grown from low-temperature solutions is described; in this case, the formation of misfit dislocations is impossible and stress relaxation occurs due to the formation of numerous inclusions at the interface. The general concept of growing high-quality mixed crystals from solutions is described, using the example of K2(Co, Ni)(SO)2 · 6H2O (KCNSH) mixed crystals. [ABSTRACT FROM AUTHOR]