Growth kinetics on the (100) and (001) faces of TGS crystals

The growth kinetics and mechanisms on the (001) and (100) faces of TGS crystals were investigated. A phase contrast microscope with a CCD camera was used to observe the growth of the crystal. We found the growth on the (001) and (100) faces at high supersaturation was mainly controlled by a BCF surface diffusion mechanism. The kinetic data for the (100) face were also fitted by the nucleation and layer growth model of two-dimension nucleation at high supersaturation. Some important growth parameters for TGS crystals, such as edge energy, activation energy, and so on, were estimated.     

Growth kinetics of (001) type faces of rochelle-salt crystals in solutions

Growth kinetic data of Rochelle-Salt crystals are presented and discussed in terms of the BCF theory. The characteristic constants for crystals grown in pure solution as well as in the impurified ones are determined. Experimental data obtained for the (001) and (210) type faces in other experimental conditions (Levina, Beliustin) are also discussed.     

In situ measurement of growth kinetics of {100} KDP crystal faces in the presence of polyphosphate impurities

The face growth rate and critical supersaturation of {100} face were in situ measured using the laser‐polarization‐interference technique in the presence of potassium pyrophosphate, trimetric sodium phosphate and sodium hexametaphosphate impurities. The polyphosphate impurities inhibit the growth rate of prismatic faces. The face growth rate as a function of supersaturation at different impurity concentrations, as well as critical supersaturation as a function of impurity concentrations, was found in good agreement with a two‐dimensional nucleation model in the pure system and Kubota and Mullin's model in the presence of impurities. The average distance L between active sites available for impurity adsorption as well as the edge free energy was calculated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

8-Thiatheophylline nitrato silver (I): Spectroscopic characterization and crystal structure

A new metal-theophylline derivative was synthesized from AgNO₃ and 8-thiatheophylline. The thermal stability of the Ag(C₆H₆N₄O₂S)(NO₃) complex was studied by TG and DSC techniques. The silver coordination has been discussed from IR,¹H-NMR and¹³C-NMR spectra. The crystal structure was established by X-ray diffraction. Ag(TTH)(NO₃) crystallizes in space groupP2₁2₁2₁ witha=6.198(1),b=12.576(2),c=13.422(2) Å andZ=4. The structure was refined toR=0.032. This complex reveals interesting features in the coordination mode of the TTH ligand. The sulfur atom and the carbonyl groups are not involved in the coordination. Silver tetrahedral coordination occurs through N7 and N9 of two different TTH ligands (Ag-N7=2.422(3) Å; Ag-N9=2.356(2) Å) and through two oxygen atoms of two different nitrato groups (Ag-O=2.435(4) and 2.518(4) Å) giving a polymeric structure.     

Growth kinetics of zinc(tris)thiourea sulphate (ZTS) crystals

Growth kinetics of zinc (tris) thiourea sulphate (ZTS) crystals investigated as a function of supersaturation is reported in this communication. Crystal growth rates were investigated normal to the (100), (010) and (001) faces under growth conditions employed for bulk crystal growth. The growth rates normal to (010) and (100) were found to follow the continuous growth model (R_G = Cσ) with respect to the supersaturation whereas the growth rates normal to (001) was found to satisfy birth and spread (B+S) model (R_G = Aσ^5/6 exp(‐B/σ)). The growth rates observed normal to the studied face are in agreement with the growth mechanism predicted from the estimated α (Jackson) factor. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Pyrolysis kinetics of silicon hydrides on a Si(100) surface

Specific features of the decomposition of silicon hydrides on a Si(100) surface have been considered. Simulation of thermodesorption hydrogen spectra revealed three possible ways of hydrogen desorption from the surface and the occurrence of only one bimolecular decomposition reaction of SiH₂ molecules. All the kinetic parameters were unambiguously determined from the comparison of the simulated and experimental spectra. The influence of the initial surface coverage on the thermodesorption spectra is also studied.     

Synthesis and crystal structure of a novel polymeric silver(I) complex

The complex of [Ag₂(μ–L)₂(μ–NO₃)₂]_n, where L?=?2–methyl–5–(2–pyridyl)–1,3,4–oxadiazole, has been synthesized and characterized by single–crystal X–ray diffraction analysis. The crystals are in triclinic system with space group P–1. Complex [Ag₂(μ–L)₂(μ–NO₃)₂]_n is a polymeric silver(I) complex bridged through the 1,3,4–oxadiazole rings and the nitrate ions, and the center Ag1(I) atoms have distorted trigonal bipyramidal geometries [AgN₃O₂].     

Synthesis and crystal structure of a silver(I) complex with dithioether ligand

The reaction of the dithioether ligand, 2,3-bis(5-methyl-1,3,4-thiadiazole-2-thiomethyl) quinoxaline (L) with AgBF₄, leads to the formation of a novel complex {[AgL](BF₄)}_∞ 1, which has been characterized by single-crystal X-ray diffraction analysis: monoclinic, space group C2/c, with a = 20.316(7) ?, b = 12.401(4) ?, c = 18.039(6) ?, β = 108.404(6)° and V = 4312(3) ?³. The crystal structure of the complex consists of 1D {[AgL]⁺}_∞ cation chain and BF₄ ⁻ anions. In 1, the coordination geometry of Ag^I center can be best described as trigonal planar coordinated by three N from two distinct L ligands. The ligand is polydentate with one end adopting a bidentate conformation to chelate an Ag^I atom and the other end monodentate to bridge another Ag^I resulting in an infinite chain along b axis. There exist Ag⋯N weak coordination, π–π stacking and F⋯S weak interactions in the complex, and these weak interactions link the 1D complex into 3D supramolecular structure and further stabilize the crystal structure in the solid state.     

Growth and characterization of Imidazolium adipate (IA) single crystal

Bulk single crystals of Imidazolium adipate (IA) were grown by solution growth method at 35 °C temperature. The solubility measurement of the material was carried out. FT-IR spectral analysis confirms the functional groups of the IA compound. Linear and nonlinear optical properties of the crystal were analyzed by UV-Vis-NIR transmittance and SHG studies. The high transparency with wide band gap is useful for optoelectronic applications are indicated. The SHG efficiency was higher than KDP. Vickers hardness study confirmed that the crystal was soft nature. Thermal stability of the material is up to 80 °C and the electrical study was carried out.     

Nd:YVO4晶体a向生长研究

采用固-液两相混合,使NdO3、Y2O3和V2O5在近常温条件下初步合成Nd:YVO4多晶原料,降低固相合成反应温度,减少V2O5在多晶原料制备过程中的挥发.讨论了a方向Nd:YVO4单晶生长条件,采用提拉法,以(100)方向进行单晶生长,得到一系列掺杂浓度的Nd:YVO4单晶.     

采用MOCVD方法在GaAs衬底上生长ZnO(002)和ZnO(100)薄膜

采用金属有机化学汽相沉积生长法（MOCVD）,在不同的衬底表面处理条件和生长温度下,在GaAs衬底上生长出了ZnO薄膜。随着化学腐蚀条件的不同,可生长出优先定位不同的ZnO（100）和ZnO（002）薄膜。该薄膜的晶体结构特性是由X光衍射谱仪（XRD）所获得的,而其光学特性是由光荧光谱仪（PL）来测的。与ZnO（002）相比,ZnO（100）薄膜具有更优越的晶体结构特性,并且在同样的生长温度下都具有相似的光学特性。对于腐蚀条件不同的GaAs衬底所进行的XPS分析结果表明,ZnO薄膜优先定位变化的主要原因在于腐蚀过程中形成的富As层。     

Growth and characteristic of Sr3Tb(BO3)3 crystal

A new borate single crystal of Sr₃Tb(BO₃)₃ with dimension Ф20×25 mm² has been grown by the Czochralski method. The grown crystal was characterized by DTA–TGA, FTIR and X-ray powder diffraction analysis. The results showed the crystal with [BO₃]^3? is congruently melting at 1351.35 °C which belongs to hexagonal structure. The hardness of Sr₃Tb(BO₃)₃ crystal is 422.5 VDH, and is equal to 5.0 moh. The thermal expansion coefficients were determined to be 2.08×10^?5/°C along (1 0 0) direction and 7.43×10^?6/°C along (0 0 1) direction and the transmission spectrum was measured in 320–1800 nm at room temperature. The magnetic properties of the single crystal were studied which showed its paramagnetism and magnetic anisotropy. The specific Faraday rotation of single crystal was measured at room temperature in 532, 633, and 1064 nm wavelength. The Verdet constants and magneto-optical figures of merit were investigated. The primary emphasis is laid to explore a new magneto-optical material, all the magneto-optical properties of Sr₃Tb(BO₃)₃ are comparing to the ones of TGG.     

Benztropine mesylate: crystal structure and kinetics of dehydration

The crystal structure of benztropine mesylate has been determined. It is orthorhombic, Pbca, with a = 12. 885(8)Å, b = 32.012(9)Å, and c = 10.027(3) Å. It exhibits similar packing to that seen in the previously reported crystal structure of benztropine mesylate monhydrate. X-ray powder diffraction patterns have been used to identify the anhydrous and monohydrate forms. The dehydration of the monohydrate follows a first-order reaction mechanism with activation energy of 92(8) kJ mol^–1.     

Growth and characterization of Ytterbium doped KGd(WO4)2 single crystal

Single crystals of Ytterbium doped KGd(WO₄)₂ were grown by Top Seeded Solution Growth technique using K₂WO₄ as flux system. The growth parameters were optimised to get optically transparent crystals. Variation in the lattice parameters were observed in comparison to the pure KGd(WO₄)₂ crystals. The absorption spectra recorded for the Yb:KGW confirms the material suitability for diode pumped solid state lasers. The vibrational studies carried out using spontaneous Raman spectra indicate the strong anionic vibration of the material. PL spectra show the lasing channel of the laser active ions present. Stimulated Raman scattering analysis confirms the material as an efficient Raman laser material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of a novel NLO crystal bis-glycine hydrogen chloride (BGHC)

Single crystals of bis-glycine hydrogen chloride (BGHC), a semiorganic nonlinear optical (NLO) material, have been grown by slow solvent evaporation technique. Good optical quality single crystals with dimensions up to 33×5×5 mm³ are obtained. The crystals are characterized by optical transmission spectrum, FTIR and X-ray diffraction studies. The thermal stability of the crystal is studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The second harmonic generation (SHG) efficiency of BGHC was found to be 5.6 times that of KDP. The laser damage threshold values studied in single shot mode indicates that BGHC crystal possesses a fairly high value of 9.8 GW/cm² and thus the NLO studies confirmed the superiority of BGHC over KDP and urea crystals. The dielectric constant of the crystal was studied as a function of frequency and the results are discussed.     

Cs2Ni(SO4)2 · 6H2O (CNSH) crystal: Growth and some properties

Large single crystals of cesium-nickel sulfate hexahydrate Cs₂Ni(SO₄)₂ · 6H₂O of optical quality were grown for the first time. The crystal structure and the optical and thermogravimetric properties of this compound were investigated.     

Second neighbours velocities and size of faces in crystal habit

Influence of growth velocities of first and second neighbours on the presence and size of the face in the crystal habit has been studied. It was established and confirmed that the consecutive neighbour affects the face size only after the disappearance of the previous neighbour. The formula for critical growth velocity governing disappearance of faces has been discussed.     

Growth and characterization of Nd:CLNGG crystal

The disordered laser crystal neodymium-doped calcium lithium niobium gallium garnet (Nd:CLNGG) was successfully grown by the Czochralski method. Its thermal properties, including the average linear thermal expansion coefficient, thermal diffusion coefficient, specific heat, and thermal conductivity were measured, and continuous-wave (CW) laser performance at 1.06 μm was demonstrated. The maximum power of 1.48 W was achieved with corresponding optical conversion efficiency of 12.4% and slope efficiency of 16.2%.     

Growth and characterization of non‐linear optical crystal ZnCd(SCN)4

Single crystals of ZCTC with dimension up to 5x2x3mm³ were grown from aqueous solution by slow solvent evaporation method and the grown crystals were confirmed by single XRD and CHN analysis. The SHG efficiency of ZCTC was evaluated using Kurtz Perry technique. Its efficiency was found to be nearly 12 times that of urea when studied with the fundamental wavelength of 1064 nm. The mechanical properties of the grown crystal have been investigated by Vickers microhardness testing. The thermal parameters such as the thermal diffusivity (α), thermal effusivity (e), thermal conductivity (k) and heat capacity (c_p) of ZCTC were measured by an improved photopyroelectric (PPE) technique and the results were discussed. The TG/DTG studies reveal that the decomposition of the sample begins around 350°C. The photoconducting nature of ZCTC has also been investigated and reported. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and dichroic properties of LiBa12(BO3)7F4 crystal

The bulk crystals of LiBa₁₂(BO₃)₇F₄ were obtained from two flux compositions by the top seeded solution growth method. Crystals grown from BaCO₃:BaF₂:H₃BO₃:Li₂CO₃ = 3:3:3:1 charge were found to have a distinct linear dichroism effect at 0.35–0.65 and around 0.73 μm. This suggests application of the material in the production of polarizing filters and attenuators for visible range lasers.