Investigation of SR method grown 0 0 1 directed KDP single crystal and its characterization by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, optical and hardness studies

0 0 1 directed potassium dihydrogen orthophosphate (KDP) single crystal was grown by Sankaranarayanan–Ramasamy (SR) method. The 0 0 1 oriented seed crystals were mounted at the bottom of the platform and the size of the crystals were 10 mm diameter, 110 mm height. Two different growths were tried, in one the crystal diameter was the ampoule's inner diameter and in the other the crystal thickness was less than the ampoule diameter. In the first case only the top four pyramidal faces were existing whereas in the second case the top four pyramidal faces and four prismatic faces were existing through out the growth. The crystals were grown using same stoichiometric solution. The results of the two growths are discussed in this paper. The grown crystals were characterized by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, UV–vis spectroscopy and microhardness studies. The HRXRD analysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. Laser damage threshold value has been determined using Nd:glass laser operating at 1054 nm. The damage threshold for the KDP crystal is greater than 4.55 GW cm⁻². The dielectric constant was higher and the dielectric loss was less in SR method grown crystal as against conventional method grown crystal. In thermal analysis, the starting of decomposition nature is similar in SR method grown KDP crystal and conventional method grown crystal. The SR method grown KDP has higher transmittance and higher hardness value compared to conventional method grown crystals.     

Growth, thermal, dielectric and mechanical studies of triglycine zinc chloride, a semiorganic nonlinear optical material

Triglycine zinc chloride, a semiorganic material, has been grown by slow solvent evaporation technique from a mixture of aqueous solution of glycine and zinc chloride in 2:1 molar ratio at room temperature. The grown crystal is up to the dimension of 45 × 23 × 18 mm³. Characterization of the crystals was made using single-crystal X-ray diffraction for obtaining unit cell parameters. Powder X-ray diffraction was recorded and the major peaks were indexed. Simultaneous thermogravimetric analysis and differential thermal analysis were carried out for the as grown crystals to determine the thermal stability of the crystal. The crystals were further characterized by UV-Vis-NIR transmission spectrum in the range of 200 to 1100 nm. Dielectric constant and dielectric loss measurements were carried out at different temperatures and frequencies. Mechanical studies were carried out on the as grown crystal.     

On the improvement of detection characteristics of trans-stilbene crystals by improving crystal perfection

Organic molecular scintillating crystals are noted for their good timing and particle discrimination process. Trans-stilbene is one such candidate noted for its good particle detection characteristics for the past five decades. Progressive strengthening of detection characteristics of trans-stilbene has been attempted by improving crystal perfection. A series of timing resolution studies have been carried out for the Bridgman grown trans-stilbene crystals under different experimental conditions. The results were compared with the previously reported values. Pulse shape discrimination process has been carried out for ²⁴¹Am and ²⁵²Cf sources and good discrimination has been obtained for gamma-alpha and gamma-neutron sources from the grown organic phosphor crystal. Electronic Publication     

Growth and characterization of l-phenylalanine nitric acid, a new organic nonlinear optical material

A new organic nonlinear optical material L-phenylalanine nitric acid [2C₉H₁₁NO₂.H⁺. NO₃⁻] (LPN), was synthesized in mixed solvent of deionised water and methanol and single crystals of LPN was grown by slow evaporation method. Transparent crystals upto 2.9 × 0.3 × 0.05 cm³ were obtained. The grown crystals have been subjected to powder X-ray diffraction studies to identify the crystalline nature. Single crystal X-ray diffractometer was utilized to measure unit cell parameters and to confirm the crystal structure. The modes of vibration of different molecular groups present in LPN were identified by FTIR spectral analysis. Transmission spectra reveals that the crystal has low UV cutoff of 295 nm and has a good transmittance in the entire visible region enabling its use in optical applications. Thermal properties of the crystals have been investigated using thermogravimetric (TG) and differential thermal analyses (DTA), which indicate that the material does not decompose before melting. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm.     

Effect of Ni on the structural, optical, thermal and dielectric properties of ADP single crystals

The effects of the addition of Ni²⁺ on the growth and various properties of ammonium dihydrogen phosphate single crystals grown from aqueous solution by the slow evaporation method have been studied. The grown crystals were subjected to HRXRD, UV-Vis, TG/DTA and dielectric studies. The structural perfection of the grown crystal has been analyzed by high resolution X-ray diffraction rocking curve measurements. UV-Vis studies show that the grown crystal has good transparency in the entire visible region which is an essential requirement for a nonlinear crystal. Higher decomposition temperature was observed from TG/DTA. Dielectric constant and dielectric loss were measured for the grown crystal for different frequencies and temperatures.     

Growth and characterization of Yb doped garnet crystals for scintillator application

Several concentration of Yb-doped Lu₃Al₅O₁₂ (Yb:LuAG) and Lu₃Ga₅O₁₂ (Yb:LGG) single crystals were grown by the micro-pulling-down method. The crystals were seeded-grown in the 1 1 1 direction and transparent and crack free crystals were obtained. Photoluminescence spectra and decay kinetics of these crystals were studied. Charge transfer luminescence of Yb³⁺ was observed in both crystals. Mean decay time of about 25 ns at 90 K and strong thermal quenching at room temperature was measured for Yb 5%:LuAG. Radioluminescence intensity was compared to the standard BGO sample.     

Studies on Ag and Li ions irradiated LAHCl single crystals

Semi-organic single crystals of LAHCl were grown by unidirectional solution growth method. The grown single crystals were subjected to Ag⁸⁺ and Li⁴⁺ ions irradiation of energy 100 MeV and 50 MeV, respectively. Breaking of bonds in the irradiated LAHCl molecules and the lattice deformations are analyzed by Fourier transform infrared spectroscopy and X-ray diffraction studies, respectively. The modifications induced by ion irradiation in dielectric, mechanical stability and nonlinear optical property are studied at different ion fluence.     

Crystal growth and scintillation properties of Ce-doped sodium calcium lutetium complex fluoride

0.1%, 0.5%, 1% and 3% Ce doped scintillation crystals based on NaF-CaF₂-LuF₃ solid solutions were grown from the melt using Micro-Pulling-Down (μ-PD) method. The grown crystals were transparent and their transmittance was approximately 80% for the wavelengths longer than 320 nm. Concerning the scintillation properties, radio-luminescence peaks of the crystals were detected at approximately 330 nm. The light yield of the crystals was also measured using γ-ray (¹³⁷Cs and ²²Na) as the excitation source.     

Growth and characterization of pure and doped NLO L-arginine acetate single crystals

Single crystals of pure, Cu²⁺ and Mg²⁺ doped L-arginine acetate (LAA) were grown successfully by slow evaporation technique. In order to improve the device characteristics of LAA crystals, metal dopants of Cu²⁺ and Mg²⁺ were incorporated into the parent crystals. The grown pure and doped crystals were confirmed by X-ray powder diffraction studies. The pure and doped crystals were characterized by Fourier transform Raman (FT-Raman) and thermal studies. Absorptions of these grown crystals were analysed using UV-Vis-NIR studies, and it was found that these crystals possess minimum absorption in the entire visible region. Nonlinear optical studies of pure and doped crystals were carried out and it reveals that the dopants have increased the efficiency of LAA crystals.     

Unidirectional growth of <101>glycine zinc chloride single crystal by Sankaranarayanan-Ramasamy method

Single crystals of glycine zinc chloride (GZC), a semi-organic compound, were grown by conventional as well as unidirectional Sankaranarayanan-Ramasamy (SR) methods. Transparent GZC crystal of diameter 15 mm and length 50 mm was obtained by employing SR growth method. The average growth rate along <101> is 0.32 mm/day and 1.25 mm/day for crystals grown by conventional and SR methods. The crystals grown by conventional and SR methods were analyzed using chemical etching, UV-Vis and Vickers microhardness. The results show that SR method grown crystals exhibit higher transmittance and hardness possessing less dislocation density as against crystals grown by conventional method.     

Bulk crystal growth of Mg2Si by the vertical Bridgman method

Mg₂Si were grown by the vertical Bridgman (VB) method in crucibles made of chemical vapor deposition (CVD) pyrolytic graphite (PG) in order to minimize the reaction and sticking of molten Mg-Si during growth. Congruent crystallization was derived from a stoichiometric melt of Mg₂Si, and incongruent crystallization was derived from nonstoichiometric melts having Mg/Si ratios of 85:15, 70:30 and 60:40. Grown samples were characterized by X-ray diffraction and electron-probe microanalysis, and their power factors were calculated from the Seebeck coefficients and electrical conductivities measured from room temperature to 773 K. The grown crystals were single-crystal-like and had high Seebeck coefficients at the temperatures from 500 to 773 K. A sample derived from a stoichiometric melt had a Seebeck coefficient of −470 μV/K and the highest power factor, 7.8×10⁻⁶ W/cm K² at 373 K, was calculated for the sample derived from a melt with an Mg/Si ratio of 70:30.     

Investigation on the defect structure and light-induced scattering of LiNbO3:Fe:Mg:Zr crystals with various Li/Nb ratios

A series of LiNbO₃:Fe:Mg:Zr single crystals with various Li/Nb ratios in the melt were grown by the Czochralski method in the air. The ultraviolet–visible and infrared transmittance spectra were measured to investigate the defect structures of these crystals. A new vibration peak of 3502 cm⁻¹ was observed in infrared transmittance spectra. The sequence of substitution was concluded according to the spectroscopic characterization. The light-induced scattering of LiNbO₃:Fe:Mg:Zr crystals was characterized quantitatively via the incident exposure energy, and the relationship between the defect structures and light-induced scattering was discussed.     

Studies on synthesis,growth and characterization of a novel third order nonlinear optical 4-Dimethylaminopyridinium p-Toluenesulfonate single crystal

Good quality single crystals of 4-Dimethylaminopyridinium p-Toluenesulfonate (4DMAPPTS) possessing third order nonlinearity were grown by slow evaporation solution technique (SEST). Single crystal X-ray diffraction analysis reveals that 4DMAPPTS belongs to monoclinic crystal system with centrosymmetric space group P2₁/n. FT-IR spectral studies were carried out to identify the functional groups present in 4DMAPPTS. NMR spectral study confirms the molecular structure of the grown crystal. Dielectric measurements were made over a wide range of frequencies for different temperatures. The grown crystal was subjected to Vickers microhardness test to study the mechanical property. The etching studies reveal the growth pattern and dislocations present in the grown title crystal. The important optical parameters such as absorption coefficient, extinction coefficient, refractive index and optical band gap were estimated from UV–Visible spectral analysis. The negative third order nonlinear optical parameters like refractive index (n₂), absorption coefficient (β) and susceptibility (χ⁽³⁾) were estimated by Z-scan studies.     

Synthesis,growth and characterization of π conjugated organic nonlinear optical chalcone derivative

A new potentially useful nonlinear optical organic material, 1-(5-chlorothiophen-2-yl)-3-(2,3-dimethoxyphenyl)prop-2-en-1-one, has been synthesized and grown as a high-quality single crystal by the slow evaporation technique. The grown crystals were characterized by FT-IR, NMR, thermal analysis, and UV–visible spectroscopy. The material is thermally stabile up to 111 °C. The mechanical property of the grown crystals was studied using Vickers microhardness tester and the load dependence hardness was observed. The third order nonlinear optical properties of the material such as real and imaginary part of χ⁽³⁾, nonlinear absorption coefficient and nonlinear refractive index were determined using nanosecond laser pulses at 532 nm wavelength by employing Z-scan technique. The nonlinear refractive index is found to be of the order of 10⁻¹¹ cm² W⁻¹. The magnitude of third order susceptibility is of the order of 10⁻¹³ esu. The observed increase in the third order nonlinearity in these molecules clearly indicates the electronic origin. The compounds exhibit good optical limiting at 532 nm. The best optical limiting behavior of this molecule is due to the substituted strong electron donor.     

Investigation on structural,optical, thermal,mechanical and dielectric properties of l-proline cadmium chloride monohydrate single crystals: An efficient NLO material

In the present work, we have grown single crystals of l-proline cadmium chloride monohydrate (LPCCM) by slow evaporation solution technique (SEST) at room temperature and recorded their live growth kinetics with the help of inverted microscope. Crystal size at various stages of growth and its corresponding morphology was also recorded. Powder X-ray diffraction (PXRD) analysis of LPCCM single crystals confirmed the orthorhombic structure. Respective values of crystallite size, strain and dislocation density have been calculated using PXRD data. Metal complex coordination of the single crystal is studied by FTIR spectroscopic. The optical properties of the grown crystals were investigated through UV–VIS spectroscopic studies and shows that the crystals have very low absorption in entire characterized wavelength range 200–800 nm. The optical band gap was calculated and found to be ∼5.6 eV. Optical constants of the material is determined by theoretical calculations. The chemical etching study was also carried out to study the density of defects in the grown crystals. The photoluminous excitation and emission spectra and thermal property by TGA/DTA curve were recorded. Further, the mechanical properties have been studied using Vicker's microhardness tester as well as many parameters such as fracture toughness (K_c), Brittleness index (B_i) and yield strength (σ_ν) are presented. Dielectric studies have been carried out with varying frequency and temperatures.     

Morphology controllable synthesis of ZnO crystals—pH-dependent growth

ZnO crystals were grown through a solution-based chemical route at ambient pressure and low temperature. It was found that the solution pH is a dominative factor in determining the morphology of crystals: Rod-like ZnO crystals are apt to be formed at near neutral condition, whereas flower-like structured ZnO crystals are preferred to be formed at higher solution pH. By monitoring the reaction intermediates during the ZnO growth process, it was realized that the crucial role of solution pH in determining the morphology of ZnO crystals is to control the structure of the primary reaction intermediates at the early stage of ZnO growth. Moreover, by appreciate controlling the solution pH together with Zn²⁺ concentration, various ZnO crystals of rod-like, dumbbell-like and even more complex flower-like structures were obtained without any template, and a pH-dependent morphology controllable growth mechanism is suggested.     

Growth, linear and nonlinear optical and, laser damage threshold studies of organometallic crystal of MnHg(SCN)4

Single crystals of bimetallic MnHg(SCN)₄ (abbreviated as MMTC) are grown by slow cooling method and the second and third order optical nonlinearities are investigated by Kurtz and Perry powder SHG test and single beam Z-scan technique respectively. The influences of SCN ligand in modifying the NLO properties are discussed and the results are compared with other organometallic crystals. The nonlinear refractive index, absorption coefficient and third order susceptibility are estimated to be −1.88 × 10⁻¹¹ cm²/W, 8.65 × 10⁻⁶ cm/W and 6.58 × 10⁻⁹ esu, respectively. The optical absorption of MMTC single crystal was recorded and the corresponding direct band gap is found to be 4.2 eV. The phase matching and laser induced damage threshold studies are also carried out. The FT-IR and photoluminescence spectroscopic techniques were employed to identify the composition and luminescence nature of the crystal.     

Anisotropic behaviour of semiconducting tin monosulphoselenide single crystals

Single crystals of ternary mixed compounds of group IV-VI in the form of a series, SnS_xSe_1-x (wherex = 0, 0.25, 0.50, 0.75 and 1), have been grown using direct vapour transport technique. The grown crystals were characterized by the X-ray diffraction analysis for their structural parameter determination. All the grown crystals were found to be orthorhombic. The microstructure analysis of the grown crystals reveals their layered type growth mechanism. From the Hall effect measurements Hall mobility, Hall coefficient and carrier concentration were calculated with all crystals showingp-type nature. The d.c. electrical resistivity measurements perpendicular toc-axis (i.e. along the basal plane) in the temperature range 303–453 K were carried out for grown crystals using four-probe method. The d.c. electrical resistivity measurements parallel to c-axis (i.e. perpendicular to basal plane) in the temperature range 303–453 K were carried out for the same crystals. The electrical resistivity measurements showed an anisotropic behaviour of electrical resistivity for the grown crystals. The anisotropic behaviour and the effect of change in stoichiometric proportion of S and Se content on the electrical properties of single crystals of the series, SnS_xSe_1-x (wherex = 0, 0.25, 0.50, 0.75 and 1), is presented systematically.     

Growth of ZnSiP2 from tin solution and temperature composition diagram of the ZnSiP2: Sn system

ZnSiP₂ crystals (1 cm or more in length) have been grown from tin solution on a reproducible basis. The dimensions of the largest crystals obtained were 1.7×0.25×0.03 cm³ and 2×0.1×0.02 cm³. The temperature of the reaction region was 1050 to 1080° C and the cooling rate used to form these crystals was 7.5°C h^–1.A practical temperature-composition section of the ZnSiP₂:Sn phase diagram has been determined by differential thermal analysis, X-ray diffraction measurements and microscopic studies. The resulting information on the liquidus temperature variation with composition served to give better control of ZnSiP₂ growth from tin solution. It was concluded that ZnSiP₂ reacted eutectically with Sn and the eutectic composition was close to 100%.     

Effect of rotation of feed and seed rods on the quality of Na0.75CoO2 single crystal grown by traveling solvent floating zone method

High purity Na_0.75CoO₂ single crystals have been grown by floating zone method. We found the rotation of feed and seed rods play a crucial role in growing high quality single crystal. Systematic investigations suggest the occurrence of a phase separation at microscopic level, such as the separation into Na-rich and Na-poor domains during the growth, and formation of impurity phase(s) depending on growth conditions. Na_xCoO₂ (x = 0.30, 0.60) crystals have been prepared by sodium deintercalation from Na_0.75CoO₂. Powder X-ray and energy dispersive X-ray analyses have confirmed the phase purity and homogeneity of the samples. Magnetic susceptibility measurements of x = 0.60 and 0.75 crystals indicate a bulk phase transition at 22 K and an anomaly around 339 K and 334 K respectively which are attributed to structural transition. In addition some unique features related to Na_0.60CoO₂ were observed.