Growth and properties of CuInS2 single crystals

CuInS₂ single crystals 14–16 mm in diameter and up to 40 mm in length were grown by the traveling solvent method. The crystals were found to ben-type, with a conductivity of 0.1–10 S/cm, carrier concentration of 10¹⁶–10¹⁷ cm⁻³, and carrier mobility of 150–220 cm²/(V s). The anisotropic thermal expansion of the crystals was measured.     

Growth and properties of strontium cobaltate single crystals

Single crystals of strontium cobaltate with oxygen-deficient composition have been prepared by the floating-zone method using a lamp image furnace. Chemical and X-ray analyses showed that the composition was SrCoO_2.70 with a doubled perovskite structure of cubic cells, a ₀=7.710±0.001 Å. The crystal was ferromagnetic and its Curie temperature was 150 K. The effective Bohr magneton per ion of Co⁴⁺ was 1.21, suggesting that Co⁴⁺ is almost in the low spin state.     

Growth and some properties of sodium-cadmium formate single crystals

The growth of sodium-cadmium formate NaCd(HCO₂)₃ single crystals by slow cooling method and their characterization by selective stching, X-ray diffraction and IR absorption spectral techniques are reported. The dislocation density in the crystals is found to be 5·10² ? 2·10³ cm^?2. The compound crystallizes in orthorhombic unit cell with space group Pcca and Z = 4. The influence of metal ion on carboxylate stretching frequencies of polycrystalline samples is investigated and the possible correlations between spectra and structure considered.     

Growth and electrical properties of mercury indium telluride single crystals

A novel photoelectronic single crystal, mercury indium telluride (MIT), has been successfully grown by using vertical Bridgman method (VB). The crystallinity, thermal and electrical properties of the MIT crystal were investigated. The results of X-ray rocking curve show that the as-grown MIT crystal has good crystal quality with the FWHM on (3 1 1) face of about 173 in. DSC measurement reveals that the Hg element is easy to solely evaporate from the compound when the temperature is higher than 387.9 °C in the open system. Hall measurements at room temperature show that the resistivity, carrier density and mobility of the MIT crystal were 4.79 × 10² Ω cm, 2.83 × 10¹³ cm⁻³ and 4.60 × 10² cm² V⁻¹ s⁻¹, respectively. The reduction of carrier mobility and the increase of the resistivity are related to the adding of In₂Te₃ into HgTe, which changes the energy band structure of the crystal.     

Growth and properties of benzil doped benzimidazole (BMZ) single crystals

In the present work, we have made an attempt to study the effect of benzil doping on the properties of benzimidazole single crystals. For this purpose we have grown pure and benzil doped benzimidazole single crystals by vertical Bridgman technique. The grown crystals were characterized by various characterization techniques. The presence of dopants confirmed by powder X-ray diffraction (XRD). Crystalline perfection of the grown crystals has been analysed by high-resolution X-ray diffraction (HRXRD). The transmittance, electrical property and mechanical strength have been analysed using UV-vis-NIR spectroscopic, dielectric and Vicker's hardness studies. The relative second harmonic generation efficiency of pure and doped benzimidazole crystals measured using Kurtz powder test.     

Growth of lithium doped silver niobate single crystals and their piezoelectric properties

Lithium doped silver niobate (Ag_1−xLi_xNbO₃, 0 < x < 0.1) is one of the candidate materials for lead-free piezoelectric materials. In this study, Ag_1−xLi_xNbO₃ single crystals were successfully grown by a slow cooling method. Crystal structure was assigned to perovskite-type orthorhombic (monoclinic) phase. Dielectric properties were measured as a function of temperature. As a result, with increasing lithium contents, the phase transition at around 60 °C was shifted to lower temperature while the phase transition at around 400 °C was shifted to higher temperature. On the basis of these peak shifts, the lithium contents in Ag_1−xLi_xNbO₃ single crystals were determined. Moreover, P–E hysteresis measurement revealed that pure silver niobate crystal was weak ferroelectrics with P_r of 0.095 μC/cm² while Ag_0.9Li_0.1NbO₃ (ALN10) crystal was normal ferroelectrics with P_r of 10.68 μC/cm². About this ALN10 crystal, polling treatment was performed and finally piezoelectric properties were measured. As a result, high electromechanical coupling coefficient k₃₁ over 70% was observed.     

Review: Review of electrooptic and ferroelectric properties of barium sodium niobate single crystals

Barium Sodium Niobate (BNN) belongs to tungsten bronze type Ferroelectric material. The non linear coefficients of BNN are twice that of LiNbO₃. Large single crystal of BNN is useful in frequency doubling applications because its conversion efficiency and resistance to optical damage are superior to LiNbO₃. Present review describes the preparative details, sturcture, ferroelectric and electro optic properties of BNN.     

Growth of single crystals of meta-nitroaniline and the evaluation of its electro-optic properties

Single crystal boules of meta-nitroaniline of good optical quality have been grown. Metanitroaniline exhibits a strong linear electro-optic effect, has a low refractive index and low permittivity, making it attractive for use in high-speed electro-optic modulators and deflectors.Currently on study leave at Department of Electrical Engineering, Imperial College, London.     

Growth and habit modification of sodium chlorate crystals

Single crystals of sodium chlorate were grown in the presence of selective impurities. The morphology of these crystals changed completely from cubic to tetrahedral form. Experiments were performed in the presence of different concentrations of impurities to ascertain their role in modifying the habit of these crystals. The presence of impurity in the solution was found to affect the habit of the crystals, although it does not appear to enter into the lattice.     

Growth and scintillation properties of Yb doped aluminate, vanadate and silicate single crystals

For the purpose of quick screening for charge transfer (CT) transitions of Yb³⁺ in various hosts, (Lu_1−xYb_x)₃Al₅O₁₂ (Yb:LuAG) with x=0.05, 0.15, 0.30 and (Y_1−xYb_x)AlO₃ (Yb:YAP) with x=0.05, 0.10, 0.30 were grown by the micro-pulling-down method. (Y,Yb)VO₄ with strong wetting was grown by edge defined film-fed growth method and materials, which require moderate temperature gradient, such as Ca₈(La,Yb)₂(PO₄)₆O₂ and (Gd,Yb)₂SiO₅ were grown by Czochralski method. Strong dependence of the CT luminescence decay time and intensity on temperature was observed for Yb-doped LuAG and YAP. Super fast decay with 0.85 ns decay time was observed in Yb(30%) doped YAP at room temperature. Though the emission intensity is weak at room temperature, it exceeds several times that of PbWO₄. In addition, CT luminescence of Yb:YAP occurs at longer wavelength than in BaF₂, which enables the usage of glass-based photomultiplier for the detection. In addition, higher stopping power will be expected due to the higher density host compared with BaF₂.     

Growth and electrical properties of Zn3P2 single crystals and polycrystalline ingots

A method to grow tetragonal -Zn₃P₂ single crystals from commercially available powder is reported. Thermal and growth duration conditions to increase crystal quality are given. The applicability of the Klosse-Ullersma model is discussed in this case, and optimized reactor dimensions are given. To grow polycrystalline ingots in a standard two-zone furnace from synthesis of elements, we propose a method which allows one to obtain single compact polycrystals with as-grown resistivities comparable to the best values reported for Zn₃P₂. Finally the growth of Zn₃P₂ and silver-doped Zn₃P₂ in the proportions 0.01 to 0.1 at% Ag per atom of zinc are for the first time reported. Crystallographic and electrical properties are also studied.On leave from the Departamento de Electricidad y Magnetismo, Facultat de Fisiques, Valencia, Spain.     

Growth and characterisation of KNbO2 single crystals

Abstract

The growth of good quality colourless potassium niobate (KNbO₃) single crystals is reported. Various flux compositions with corresponding starting temperatures were chosen from the phase diagram to avoid the black/blue colour formation in growth of KNbO₃ single crystals. Deviation of compositions of colourless and black crystals from the starting composition were analysed by electron spectroscopy for chemical analysis. Dielectric constant and pyroelectric coefficients were calculated with respect to temperature and the transition temperature was confirmed by differential scanning calorimetry studies. Hysteresis loops have been traced with respect to electric field.     

Growth and thermal studies of SnSe single crystals

Single crystals of SnSe have been grown by a direct vapour transport (DVT) technique. The confirmation of single crystallinity and lattice parameter determination of the grown crystals have been made by using electron and X-ray diffraction techniques respectively. The thermal analysis of the crystals has been studied by the well known TGA and DTA techniques. The results obtained during the analysis showed the stability of SnSe phase at higher temperatures. The implications of the results have been discussed.     

Growth and characterisation of TaS2 single crystals

Single crystals of tantalum disulphide have been grown by a sublimation or direct vapour transport method. Crystals as large as 15×10×0·05 mm³ grew in the form of platelets and needles above the charge which was kept well distributed within the ampoule. Characterisation of the as-grown crystals has been carried out at room temperature by x-ray diffraction. Electrical conductivity and magnetic susceptibility measurements have also been made.     

Growth of large ultratransparent KCl single crystals

This paper reports the successful realization and operation of an installation for growing single crystals of ultratransparent KCl by injecting the reactive atmosphere. The devised procedure and apparatus can be used for preparing on a reproducible basis large-single-crystalline ingots with bulk absorption at 10.6 μm approaching the intrinsic limit, as requested in high power laser applications.     

Growth of ferroelectric lead metatantalate single crystals

Liquidus relations in the “Pb(BO₂)₂”-PbTa₂O₆, Pb(VO₃)₂-PbTa₂O₆, and Pb₂V₂O₇ —PbTa₂O₆ systems were studied in order to find solvents for growing ferroelectric lead metatantalate single crystals below 1300‡C. PbO-V₂O₅ melts were shown to be suitable solvents for growing lead metatantalate crystals with both rhombohedral and tetragonal potassium tungsten bronze structures. Ferroelectric PbTa₂O₆ crystals with a Curie temperature of 265‡C were grown from vanadate fluxes.     

Growth of titanium single crystals by electrotransport

Single crystals of H.C.P. Titanium may be grown by electrolysis in solid state. Because of the low phase transformation temperature, the samples are annealed in the B.C.C. phase for the primary recrystallization. With a good control of secondary recrystallization at the B.C.C. to H.C.P. transformation, we obtain, without any contamination, single crystals of the hexagonal phase of a few centimeters length.     

Dielectric properties of LiF single crystals

The dielectric constant,, loss, tan, and a.C. Conductivity, , of high quality single crystals of LiF have been measured in the frequency range 10² to 10⁵ Hz and in the temperature range 30 to 400° C. of LiF at 30° C is 8.3 and is frequency independent; tan was below detection level (tan<0.0001). increases slowly with temperature up to about 150° C (frequency independent region) beyond which it rises rapidly, being frequency dependent with larger values at lower frequencies. A similar behaviour is exhibited by tan . The activation energy for conduction in the high temperature region is calculated to be 0.93 eV from log against 1/T graphs. Log () against 1/T plots (where is the difference between the dielectric constant at any temperature and the value at room temperature, 30° C) yields an activation energy value of 1.0 eV in the high temperature region. This activation energy is found to be independent of frequency. This agreement between the two activation energy values, one for the a.c. conductivity and the other for the increase with temperature. This suggests that the same charge carriers are responsible for the two processes in the high temperature region.     

Growth and properties of BaZnGeO4 crystals

Single crystals of BaZnGeO₄ have been grown by the Czochralski pulling method from a stoichiometric melt of barium, zinc and germanium oxides. The crystals were colourless, up to 24 mm in diameter and 35 mm length, and their composition corresponded to the formula Ba_0.978Zn_0.986Ge_1.018O₄. X-ray diffraction analysis revealed that the crystal structure was a modified BaAl₂O₄ type with the hexagonal cell parameters of a ₀=92.97 nm and c ₀=352.84 nm. Phase transitions were observed at 520 K and 1108 K from measurements of DTA, thermal dilatometry and dielectric constants, and by high temperature X-ray precession photography.