The growth and characterization of 2,4-dinitro phenyl hydrazone of benzophenone and mixed crystals

Good quality benzophenone (BP) crystals were grown by solution technique using CHCl₃ as solvent by adopting slow evaporation method at room temperature. The grown crystals were subjected to various characterization studies to analyze its purity and applications. The condensation product 2,4-dinitro phenyl hydrazone of benzophenone (DNPBP) was prepared by adopting standard procedure. Then mixed crystal of BP and DNPBP was also grown by solution growth. Both the condensation product and mixed crystals were characterized by UV, FTIR, ¹H NMR spectra. Thermal (TG and DTA) studies have proved to be very useful techniques not only to study the thermal properties of BP, DNPBP and mixed crystal but also to study their purity. Second harmonic generation (SHG) efficiency of the grown crystals was determined.     

Vibrational spectroscopic analysis of cytosine monohydrate and its copper(II) complex

Single crystals of cytosine monohydrate and its copper(II) complex were grown by slow evaporation in an aqueous solution at room temperature. The solubility studies were carried out at different temperatures in deionized water. Cytosine monohydrate and the copper(II) complex of cytosine were characterized by recording IR, Raman and UV spectra. The various vibrational modes of the crystals have been classified using factor group and site group analysis. Vibrational assignments were proposed for both the systems based on the spectral investigations.     

Structural, spectral, optical and dielectric properties of copper and glycine doped LAHCl single crystals

Cu2+ and glycine doped L-arginine monohydrochloride monohydrate (LAHCl) single crystals were grown by slow solvent evaporation technique. The grown single crystals were confirmed by X-ray diffraction study and the interaction of dopants with LAHCl molecule was identified in Fourier transform infrared spectra. The crystalline perfection of pure and doped crystals was analyzed by high resolution X-ray diffraction studies. Vickers microhardness and UV-visible spectroscopy were carried out respectively to study the mechanical stability and optical transmittance of pure and doped LAHCl single crystals. He-Ne laser of wavelength 632.8 nm was used to measure refractive index and birefringence of grown crystals. The second harmonic generation efficiency was also measured for pure and doped LAHCl single crystals using Nd:YAG laser.     

Vibrational spectroscopic studies of an organic non-linear optical crystal 8-hydroxyquinolinium picrate

8-hydroxyquinolinium picrate (8-HQP) was synthesized by the addition of equimolar quantities of 8-hydroxyquinoline (8-HQ) and picric acid (PA). Single crystals were grown from N,N dimethyl formamide (DMF) by restricted evaporation method at room temperature. The solubility of 8-HQP was determined in different solvents at various temperatures. The structural characterization of the grown crystals was carried out by X-ray diffraction. Vibrational modes were classified on the basis of group theoretical analysis and the spectral bands were compared with those of parent compounds in order to propose a tentative assignment by recording FT-IR, FT-Raman and polarized Raman spectra in different crystal orientations. The crystal possess lower cut-off at 230 nm and good transparency as confirmed by optical transmittance studies.     

Characterization of 4-chloro-3-nitrobenzophenone crystal grown by Bridgman technique

The large size 12 mm diameter 4-chloro-3-nitrobenzophenone (4C3N) single crystal has been grown by using vertical Bridgman technique. The grown crystal was confirmed by Powder X-ray diffraction analysis. The crystalline perfection of the grown crystal was examined by high-resolution X-ray diffraction study. The cutoff wavelength of the grown crystal was analyzed by optical studies. The thermal property of the grown crystal was studied by thermogravimetric and differential thermal analyses. The fluorescence spectra of grown 4C3N single crystals exhibit emission peak at 575 nm. The microhardness measurements were used to analyze the mechanical property of the grown crystal. The laser-induced surface damage threshold for the grown crystal was measured using Nd:YAG laser.     

Growth and spectroscopic characterization of a new organic nonlinear optical crystal--8-hydroxyquinoline

A novel organic nonlinear optical crystal 8-hydroxyquinoline having good optical quality has been grown by slow evaporation solution technique using methanol as solvent. The morphology of the grown crystals were identified by X-ray diffraction method. Solubility studies were made under various solvents and solvent mixtures at different temperatures. Functional groups present in the grown material have been identified using FTIR and FT Raman spectra. Transparency was tested using UV-vis spectrophotometer and the second harmonic generation was also verified.     

EPR of gamma-irradiated single crystals of 2-amino-5-nitro pyridinium L-tartrate: a NLO material

Single crystals of a non-linear optical (NLO) material 2-amino-5-nitropyridinum L-tartrate (ANPLT) were grown by solvent evaporation technique and characterized by the measurement of density, FT-IR, FT-Raman and X-ray diffraction techniques. Microhardness study and SHG test were also carried out. The EPR spectra were recorded for gamma-irradiated single crystal of ANPLT. The angular variation studies of the spectra were carried out and the principal values of g- and A-tensors were determined. The site symmetry of the radical formed is axial.     

ac susceptibility and ESR studies on vapour phase grown Cd(1-x)Mn(x)Te crystals

Single crystals of Cd(1-x)Mn(x)Te for x = 0.1, 0.2, 0.3, 0.4 and 0.5 were grown by a modified vapour phase growth technique. ac magnetic susceptibility studies were carried out in the temperature range 14-300 K. Both the real and the imaginary parts of susceptibility indicated the formation of spin-glass phase at low temperatures. ESR spectra were recorded at room temperature (300 K) at 9.4 GHz for samples of all compositions. The line width (DeltaH) increased with Mn content.     

Semiorganic nonlinear optical l-lysine sulphate growth and characterization

l-Lysine sulphate (LLS), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been synthesized. The solubility studies have been carried out in the temperature range 30–50 °C. Single crystals have been grown by slow evaporation method from an aqueous acetone solution of l-lysine and sulphuric acid. The grown crystals were bulk, bright and transparent. These crystals were characterized by X-ray and FTIR studies. Powder X-ray pattern indicates that LLS crystallizes in orthorhombic space group P2₁2₁2₁ with four unit cells. FTIR spectral studies were performed for the conformation of the l-lysine molecule and hydrogen bonds. The optical transmission spectra of the grown crystal are tested by UV–vis spectrophotometer and found that the crystal was transparent over entire visible region. The second harmonic generation test of the LLS revealed the nonlinear nature of the crystal.     

Growth and characterization of unidirectional (100) KDP single crystal by Sankaranarayanan-Ramasamy (SR) method

Unidirectional (100) potassium dihydrogen orthophosphate (KDP) single crystals were grown by Sankaranarayanan-Ramasamy (SR) method. The (100) oriented seed crystals were mounted at the bottom of the glass ampoules and the crystals of 20mm diameter, 30 mm height and 15 mm diameter, 65 mm height were grown by SR method. The grown crystals were characterized by high-resolution X-ray diffractometry anlaysis, UV-vis spectroscopy, dielectric and microhardness studies. The high-resolution X-ray diffractometry anlaysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. The SR method-grown unidirectional KDP has 15% higher transmittance compared to conventional method-grown crystals. The dielectric constant was higher and the dielectric loss was less in SR method-grown crystal. The crystals grown by SR method have much higher hardness value than conventional method-grown crystals. The quality of the crystal grown by SR method is better than conventional method-grown crystal.     

Synthesis, growth and characterization of bis (glycine) lithium molybdate—A semi-organic NLO material

Single crystals of bis (glycine) lithium molybdate [BGLM] with dimensions 20 mm × 10 mm × 5 mm were grown by slow evaporation technique. The grown crystals were subjected to powder X-ray diffraction studies. Functional groups of the crystallized molecules were confirmed by FTIR analyses. Transmission range of the crystal was determined by UV–vis–NIR spectra. Vickers microhardness test was performed on the prominent plane (0 1 1) of the grown crystal. The NLO property of the crystal was confirmed by Kurtz SHG test and compared with NLO efficiency of KDP crystal.     

Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals

Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.     

Nd3+:NaLa(WO4)2晶体的生长和光学性质

Nd3+:NaLa(WO4)2 crystals with a dimension up to 7 mm were grown from a high temperature solution using a double-crucible method. Scanning electron microscopy observations of the crystals showed that there were no small cracks on the surface of the crystals although they underwent two phase transitions when cooling down from high temperatures. X-ray diffraction studies indicated that the as-obtained product is pure low- temperature tetragonal Nd3+:NaLa(WO4)2. The absorption and fluorescence spectra for Nd3+:NaLa(WO4)2 were measured at room temperature. The absorption band at 804 nm has a wide full-width half maximum of 23 nm whose origin is discussed. The absorption and emission cross sections were calculated to be 7.24*10-20 cm2 at 804 nm and 6.54*10-20 cm2 at 1057 nm, respectively.     

I NQR and spectroscopic investigation of impurity-doped and mixed lithium iodate Li1−xHxIO3 crystals

The ¹²⁷I NQR, IR absorption and Raman spectra of impurity-doped and mixed lithium iodate Li_1−xH_xIO₃ crystals grown from water solutions with different LiIO₃/HIO₃ ratios were investigated depending on the content of the impurity hydrogen x. The NQR results suggested that, at small concentration of doping iodic acid x<0.22, the lattice dynamics of the crystal grown from water solution changes significantly though the crystal retains hexagonal symmetry. Spectroscopic studies are compatible with average hexagonal symmetry of the grown doped crystals. From the results of Raman studies at room temperature and 100 K, the concentration range of hydrogen dopant 0.22<x<0.36 was found where disordered solid solution crystals Li_1−xH_xIO₃ are formed.     

Optical Properties of Ce-Doped Lithium Niobate Crystals with Various Li/Nb Ratio

Ce-doped lithium niobate （LiNbO3） single crystals were grown from the melts with various Li/Nb molar ratios （0.750, 0.850, 0.946, 1.100, 1.250 and 1.380） by Czochralski method, while doping concentration of Ce was 0.1 mol%. Infrared spectra （IR） and Ultraviolet-visible absorption spectra （UV） of the crystals were measured to investigate the location of Ce ions and defect structure in crystals. The writing time, erasing time, photorefractive sensitivity and dynamic range were measured by two-wave coupling equipment. The results showed that Ce takes the place of Li lattice site, and the LiNbO3 crystal grown from the melt with Li/Nb ratio of 1.250 is stoichiometric crystal, which has the best properties due to the synergistic effect of Ce ion and Li/Nb ratio. Also the influence of various Li/Nb ratios on the defect structure and optical properties of the crystal was reported.     

Crystal growth and characterization of N-hydroxyphthalimide (C8H5NO3) crystal

Single crystals of N-hydroxyphthalimide (NHPH) were obtained from saturated aqueous solutions of methanol and acetonitrile by slow cooling method. The grown crystals were bright and transparent. From the crystal structure analysis it can be inferred that the crystal belongs to monoclinic system. The grown crystals were subjected to FTIR analysis for vibrational assignments. The optical transmission spectra showed excellent transmittance from 200 to 1100nm. The thermal stability and thermal decomposition of NHPH crystal have been investigated by means of thermogravimetric analysis and differential thermal analysis.     

Influence of Nd:Zn codoping in near-stoichiometric lithium niobate

Near-stoichiometric lithium niobate (SLN) crystals doped with up to 1.6 mol % Zn and codoped with various Nd concentrations in the melt (0.2, 0.5, 0.9, and 1.5 mol %) (Nd:Zn:SLN) are grown from 58.6 mol % Li(2)O using conventional Czochralski technique. Crystals are pulled at the rate of 0.35 mmh with seed rotation at 9 rpm. Concentrations of Zn and Nd in the crystal are varied by adding appropriate amounts of ZnO and Nd(2)O(3) to the starting composition. Unit cell parameters of the grown crystals are calculated by Rietveld refinement method using FULLPROFF software. Domain structure studies are carried out by chemical etching followed by microscopic examination. Dielectric studies reveal the existence of piezoelectric resonance at high frequencies. Enhancement in dielectric constant and tan delta in Nd doped samples has been attributed to the space charge polarization. Nd doped samples exhibit reduction in the relative permittivity after oxygen annealing. Transmission spectra of Nd:Zn:SLN crystals in the UV region exhibit blueshift in the cutoff wavelength. In Mid Infrared (MIR) region crystals doped with 1.6 mol % Zn have shift in the OH absorption peak from 2873 to 2833 nm. Judd-Ofelt analysis carried out on the absorption spectra of codoped crystal yields the lifetime of 104 mus for the metastable state (4)F(32). The branching ratio for the electronic transition from (4)F(32) to (4)I(112) is high compared to that for (4)F(32) to (4)I(132), indicating a higher emission cross section for the former transition. Laser damage threshold evaluated using 532 nm, 5 ns pulsed neodymium doped yttrium aluminum garnet laser, shows an increase by two orders of magnitude for crystals doped with 1.6 mol % Zn. Photorefractive damage threshold for these crystals shows an enhancement of four orders of magnitude due to increase in the photoconductivity.     

Synthesis,growth and characterization of nonlinear optical urea–ammonium chloride crystals

Semi-organic nonlinear optical urea–ammonium chloride (UAC) crystals have been grown from aqueous solution by slow evaporation technique. The lattice parameters of the grown crystals were determined by X-ray diffraction studies. The presence of functional groups was determined using Fourier transform infrared (FTIR) analysis. The thermal analysis studies indicate that the material possess optimum thermal stability. Optical absorption studies show low absorption in the entire visible region and UV cut – off is found to be at 240 nm. The presence of second harmonic generation (SHG) for the grown crystal was confirmed by Kurtz powder technique.     

Investigation on the growth and characterization of nonlinear optical single crystal of bis thiourea iron(II) sulphate

Single crystal of bisthiourea iron(II) sulphate was grown by slow evaporation technique at 303?K. The structural properties of the grown crystals were characterized by FTIR spectroscopy, UV spectroscopy and powder X-ray diffraction. FTIR and UV spectra provide information about the presence of functional groups. Thermal analysis confirms the crystal is thermally stable up to 167.02?°C.     

LD激发的ZnWO4:Er3+晶体上转换发光

采用Czochralski法生长出ZnWO₄:Er³⁺(Er=0.02mol)单晶,测量了吸收光谱和激发光谱。在波长966nm功率500mW的激光二极管(LD)激发下观察到上转换发光。强度最大的发射峰位于547和558nm,发射光谱分析表明,上转换激发过程与双光子步进吸收有关。