Crystal structure,spectroscopic studies and non‐linear optical properties of 2‐amino‐3‐nitropyridinium trichloroacetate

A new quadratic nonlinear optical crystal, 2‐amino‐3‐nitropyridinium trichloroacetate (2A3NPTCA), was synthesized and the single crystals were grown by slow evaporation method at room temperature. Single crystal X‐ray diffraction and powder X‐ray diffraction experiments were carried out in order to confirm the structure and crystalline nature of 2A3NPTCA crystal. The chemical bonding and various functional groups present in the 2A3NPTCA were identified from FT‐IR spectrum. The UV–visible–NIR transmission spectrum shows that it is suitable for frequency‐converting in the wavelength region of 431–1200 nm. Thermogravimetric (TG) and differential thermal analysis (DTA) were carried out to characterize the thermal behaviors of the grown crystals. Kurtz and Perry powder method for second harmonic generation (SHG) measurements demonstrate that 2A3NPTCA is a phase matching material and its nonlinear optical efficiency is two times that of KDP. All the above results suggest that 2A3NPTCA is a potential candidate of NLO material.     

Synthesis and characterization of 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol single crystals

The synthesis of pyrazoles and its derivatives remains of great interest due to their wide applications in pharmaceutical and agrochemical industry. The 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol was synthesized. The 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol single crystals were grown by slow solvent evaporation technique using mixture of chloroform and methanol as a solvent. Yellowish and transparent crystals having maximum dimensions of 0.005 m × 0.004 m × 0.002 m were grown. The crystals were characterized by powder XRD, FT–IR, TG–DTA–DSC and dielectric study. The crystals remained stable up to 160 °C and then start decomposing. The DSC suggested both endothermic and exothermic reactions. One broad exothermic peak was observed at 558.1 °C due to complete decomposition of the sample into the gaseous phase and reaction within the products. Thermodynamic and Kinetic parameters of decomposition were calculated by Coats–Redfern formula. The dielectric study was carried out in the frequency range from 50 Hz to 5 MHz at room temperature. The dielectric constant decreased as the frequency of the applied field increased. The variations of dielectric loss, a.c. conductivity and a.c. resistivity also studied with the frequency of the applied field. Jonscher's power law was verified for a.c. conductivity.     

Structural,thermal, mechanical and z‐scan studies on 4‐nitrophenol single crystals

4‐nitrophenol (4‐NP) single crystals have been grown by using slow evaporation and slow cooling techniques. A single crystal with size in the range of 7x3.4x1.8cm³ has been obtained by slow cooling method. The grown crystals have been subjected to various characterization studies. The powder XRD spectrum of 4‐NP reveals the good crystalline nature of the grown crystal. Single crystal XRD studies show that the crystal belongs to monoclinic system with cell parameters of a=6.09 Å, b=8.79 Å, c=11.61 Å, α=γ=90°, β=103.15°. The resultant FTIR spectrum confirms the various functional groups present in 4‐NP. Thermal analysis has been performed on the material to study the thermal stability of 4‐NP. The grown crystals belong to the category of soft materials as confirmed by Vickers Hardness tests. The optical transmiitance of 4‐NP single crystals has been measured from Vis‐IR spectroscopy study. The nonlinear optical properties have been analyzed by z‐scan technique and 4‐NP is found to be self defocusing because of its negative nonlinear refractive index. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural,thermal and optical studies on 2‐naphthol crystals

Single crystals of 2‐naphthol was grown in slow evaporation solution growth technique. Grown crystals were characterized by various characterization techniques. Powder X‐ ray diffraction studies reveal that the grown crystal belongs to monoclinic system with noncentrosymmetric space group. Vibrational bands of the various functional groups and their significance were investigated by analyzing the vibrational spectra. Melting point and the decomposition temperature of the grown crystal was premeditated from the thermal analysis. From the UV‐VIS‐NIR spectrum the electronic excitation mechanism and the transmittance abilities of the crystal was studied. Theoretical value of first static hyperpolarizability was calculated and compared with urea. Second harmonic generation efficiency of the crystal is 0.6 times that of KDP. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of 4‐(2‐hydroxyphenylamino)‐pent‐3‐en‐2‐one single crystals

4‐(2‐hydroxyphenylamino)‐pent‐3‐en‐2‐one (HPAP) was synthesized and single crystals were grown by the solution growth technique using methanol as a solvent. The crystals having orthorhombic symmetry were characterized by single crystal XRD, FTIR spectroscopy, NMR spectroscopy, TGA, DSC and dielectric studies. Very less variation in the value of dielectric constant is found for different frequencies of applied field. The crystals were exhibiting positive photoconductivity and poor NLO responses. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal growth,thermal and optical studies of L‐histidine tetrafluoroborate: A semiorganic NLO material

L‐histidine tetrafluoroborate (L‐HFB), a semiorganic nonlinear optical (NLO) material has been synthesized and characterized by elemental analysis and FT–NMR spectroscopic studies. Solubility of L‐HFB has been determined in water and ethanol. The single crystals with dimensions 15 x 12 x 3 mm³ were grown by slow evaporation technique under two different pH conditions. The effect of pH on the morphology of the crystals have been studied. The grown crystals of both pH values has been subjected to single crystal X‐ray diffraction to determine the unit cell dimensions and morphology. The thermal stability has been analyzed by TGA and DTA. The microhardness test was carried out in (001) plane and the hardness coefficient was calculated. The birefringence values (Δ_n) were determined in the wavelength region 5540–6460 Å. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of 4‐Aminopyridinium‐4‐nitro phenolate single crystals

Organic optical material 4‐Aminopyridinium‐4‐nitro phenolate (4AP4NP) has been synthesized, and single crystals of size 20 x 14 x 6 mm³ have been grown from acetone solvent at room temperature by solvent evaporation technique. The grown crystals have been characterized by X‐ray diffraction to determine the cell parameters, and by FT‐IR technique to confirm the formation of the expected compound. The crystal belongs to monoclinic crystal system with space group P2₁/a.The structural perfection of the grown crystals has been analyzed by high‐resolution X‐ray diffraction (HRXRD) rocking curve measurements. The thermal stability of the compound has been determined by TG‐DTA curves. The transmittance of 4AP4NP has been used to determine the refractive index n; the extinction coefficient K and both the real ε_r and imaginary ε_i components of the dielectric constant as functions of photon energy. The optical band gap of 4AP4NP is 2.4 eV. The dielectric and mechanical behavior of the specimen was also studied. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Characterization of gel grown iron‐manganese‐cobalt ternary levo‐tartrate crystals

In the present investigation, iron–manganese–cobalt ternary levo‐tartrate crystals of different compositions have been grown by single‐diffusion gel growth technique in silica hydrogel medium. The metallic composition in the crystals was estimated by EDAX. The coloration of the crystals changed with composition of metallic content. The powder XRD study suggested the crystalline nature and indicated the presence of some extra phases. The grown crystals were characterized by FT‐IR spectroscopy, TGA, dielectric and Vibrating Sample Magnetometer (VSM) studies. The FT‐IR study suggested the presence of O‐H, C=O, C‐O and metal‐oxygen bonds. The effect of composition of metallic content was observed in certain absorption regions in FT‐IR spectra. The thermal stability of the crystals was studied by thermogravimetry and the kinetic and thermodynamic parameters of dehydration were calculated. The effect of composition of ternary levo‐tartrate was observed in dielectric study. The dielectric study was carried out in the frequency range of applied field from 500 Hz to 1 MHz. The variations in dielectric constant, dielectric loss, a.c. resistivity and a.c. conductivity with frequency of applied field were studied. VSM study suggested that all crystals were of paramagnetic nature. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Gel growth and characterization of β ‐DL‐methionine

DL‐Methionine [C₅H₁₁NO₂S] is one of the essential amino acids in humans. It has two crystalline forms, viz., α‐ and β‐ methionine. In the present study, β ‐ form is crystallized in silica gel; under suitable pH conditions by single diffusion method. The grown crystals were characterized by density measurement and single crystal X‐ray diffraction. Fourier transform infrared (FTIR) spectroscopic studies, thermal analysis and scanning electron microscopic (SEM) studies were also made as part of the structural studies. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical,mechanical and thermal properties of p‐bromoacetanilide

Solubility and metastable zonewidth were estimated for p‐Bromoacetanilide. Employing slow evaporation method crystals of size 22x17x6 mm³ and 38x25x10 mm³ were grown at a constant temperature of 40°C and room temperature respectively from methanol solution. The cell dimensions were obtained by single crystal X‐ray diffraction study. The placement of protons was identified from NMR spectral analysis. UV‐Visible and fluorescence spectral analyses were carried out for the grown crystals. Vickers microhardness test was performed on the prominent (110) of the as grown crystal. Thermogravimetric and differential scanning calorimetric studies were carried out to determine the thermal properties of the grown crystal. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and thermal studies on pure ADP,KDP and mixed K1‐x(NH4)xH2PO4 crystals

The investigations on the formation of mixed crystals of ammonium dihydrogen orthophosphate (ADP) and potassium dihydrogen orthophosphate (KDP) i.e. potassium ammonium dihydrogen phosphate, K_1‐x(NH₄)_xH₂PO₄ have been presented in this paper. Pure and mixed crystals of ADP and KDP have been grown by slow evaporation technique from the supersaturated solution at an ambient temperature 26±1 °C for ammonium concentration x in the range 0.0 ≤ x ≤ 1.0 in the case of mixed crystals. Crystal compositions were determined by flame atomic absorption spectroscopy and chemical analysis. The results of the X‐ray analysis of the grown crystals are also reported. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study the kinetic process of dehydration and the high temperature phase behaviour. DTA showed the distinct thermal events attributed to dehydration of ADP, KDP and K_1‐x(NH₄)_xH₂PO₄. The results of thermal analysis and chemical analysis are consistent with each other. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth,optical and thermal studies of nonlinear optical L‐arginine perchlorate single crystals

A potentially useful semiorganic nonlinear optical (NLO) material, L‐arginine perchlorate, has been synthesized and bulk crystals have been grown by slow cooling technique. The grown crystals were characterized by single crystal X‐ray diffraction, UV‐Vis‐NIR spectroscopy, FT‐IR, thermal analysis and SHG measurements. The grown crystals were thermally stable upto 153°C and exhibit SHG efficiency of about 0.17 with respect of Urea. The etching studies have been carried out on the grown crystal. LAPC has good optical transmission not only in the visible range, however, also in the near UV part of the spectra and hence it is a potential material for nonlinear frequency conversion. The refractive index was measured by the Brewster's angle method. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth behaviour of bulk GaN single crystals grown with various flux ratios using solvent‐thermal method

Bulk GaN single crystals were grown using a solvent‐thermal method. They were grown for 200 h at 600 °C and 800 °C using 8 MPa of N₂ gas and 1–3 mm sized pyramid GaN single crystals. Pure Na, NaN₃ and Ca were used as the flux. The mole fraction of the [flux]/([flux] + [Ga]) was 0.30–0.67. The growth behavior differed according to the flux ratio. The quality of the bulk GaN single crystals was improved by increasing the flux ratio. The bulk GaN single crystals formed by spontaneous nucleation were deposited on the BN crucible wall and bottom during the first step of synthesis. The wurtzite structure of the GaN grown single crystal was confirmed by x‐ray diffration. The chemical composition was analyzed by electron probe microanalysis. The quality and optical properties of the GaN single crystal were examined by Raman spectroscopy and photoluminesence analysis. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal growth of zirconium‐doped KTiOPO4 crystals in the K2O‐P2O5‐TiO2‐ZrF4 system

Zirconium‐doped KTiOPO₄ (KTP) crystals were grown using a high temperature flux method in the K₂O‐P₂O₅‐TiO₂‐ZrF₄ system. The dopant content in the single crystals with general composition KTi_1‐xZr_xOPO₄ (where x = 0 – 0.026) strongly depends on zirconium concentration in the homogeneous melts. AES‐ICP method and X‐ray fluorescence analysis were used to determine the composition of the obtained crystals. Phase analyses of the products were performed using the powder XRD. The structures of KTiOPO₄ containing different quantities of Zr were refined on the basis of single crystal XRD data. Applying ZrF₄ precursor for zirconium injection into the flux allowed growing the zirconium‐doped KTP crystals at 930–750°C. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,crystal growth and properties of the charge transfer complex adduct of 2‐nitro aniline with picric acid – An organic non‐linear optical material

The organic NLO material 2‐nitro aniline and picric acid (2NAP) was synthesized, needle shaped single crystals of dimension 10 × 1 × 0.8 mm^‐3 were grown by slow evaporation solution growth technique from the saturated solution of the title compound in chloroform at ambient temperature. The material was characterized through elemental analysis, powder XRD, ¹H NMR, ¹³C NMR and FTIR techniques. The various planes of reflection have been identified from the XRD powder pattern. The formation of the charge transfer complex was confirmed by UV‐VIS spectroscopy. The thermal stability of the crystals was investigated using TG/DTA analyses techniques. The second harmonic generation (SHG) efficiency of the material was estimated using Nd: YAG laser as source. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structure and characterization of a novel organic optical crystal: 4‐chloro‐3‐nitrobenzophenone

Single crystals of a novel organic material, 4‐Chloro‐3‐Nitrobenzophenone (4C3N) were grown from acetone solution employing the technique of controlled evaporation. 4C3N belongs to the Orthorhombic system, with a = 12.9665(11) Å, b = 7.4388(6) Å, c = 24.336(2) Å, α = β = γ = 90°. FT‐IR study has been performed to identify the functional groups. The transmittance of 4C3N has been used to calculate the refractive index n; the extinction coefficient K and both the real ε_r and imaginary ε_i components of the dielectric constant as functions of photon energy. The optical band gap of 4C3N is 2.7 eV. Thermo gravimetric analysis and differential thermal analysis have also been carried out, and the thermal behavior of 4C3N crystal has been studied. The mechanical properties have been investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photoacoustic studies on two new organic NLO materials: L‐threonine and L‐prolinium tartrate

Photoacoustic spectroscopy (PAS) is a non‐destructive testing (NDT) tool and used here for analyzing the physical properties such as thermal diffusivity, thermal diffusion length, thermal conductivity and thermal effusivity of L‐Threonine and L‐Prolinium tartrate. These two crystals belong to a group of recently developed NLO materials, in our laboratory. The single crystals of the two compounds were grown by using submerged seed solution growth method. Characterization of the crystals was made by using single crystal X‐ray diffraction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dielectric and microhardness studies on L‐citrulline and L‐ascorbic acid admixture TGS crystals

Single crystals of amino acid doped (L–citrulline, L‐ascorbic acid) triglycine sulphate were grown by slow evaporation technique. The lattice parameters and crystalline quality were confirmed by powder X‐ray diffraction studies. The presence of functional groups in the grown crystals was confirmed by Fourier transform infrared spectrum analysis. The dielectric studies were carried out to identify the phase transition temperature and the dielectric constant was found to be less for both the doped crystals than pure triglycine sulphate crystal. Micro hardness studies were carried out using Vickers pyramidal indentation technique at room temperature showed a decrease in hardness due to doping. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and properties of an organometallic nonlinear optical crystal: bis(isothiocyanato)‐bis(4‐methylpyridine)zinc(II) (Zn(SCN)2(C6H7N)2)

Bis(isothiocyanato)‐bis(4‐methylpyridine)zinc(II)(Zn(SCN)₂(C₆H₇N)₂), (abbreviated as ZBNC) single crystals of optical quality have been grown from acetone solution by the slow temperature‐lowering method. Its solubilities at different temperatures in acetone were measured. The X‐ray powder diffraction (XRPD) spectroscopy of ZBNC crystal was performed at room temperature. The second harmonic generation (SHG) efficiency was determined by powder technique of Kurtz and Perry using Nd:YAG laser, which is equivalent to KDP crystal. The thermal decomposition process was characterized by thermal gravity and differential thermal analysis (TG\DTA). The specific heat of the crystal is 1440.67 J/mol·K at 325 K. The IR spectrum was recorded in the 500∼3500 cm^–1 region, using KBr pellets on a Nicolet 170sx FT‐IR spectrometer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,spectral, thermal and NLO properties of N,N ‐Dimethyl anilinium picrate

The crystalline substance N,N ‐dimethyl anilinium picrate(DMAP) was synthesized and the single crystals of the title compound were grown by slow evaporation solution growth technique at room temperature. The crystalline nature of the material has been confirmed by powder X‐ray diffraction method. The elemental analysis data confirm the stoichiometry and hence the molecular formula of the synthesized material. The formation of the charge‐transfer complex has been confirmed by UV‐visible spectral data. The infrared and ¹H NMR spectroscopic data indicate a charge transfer activity associated with a proton transfer from the acceptor to the donor followed by intermolecular hydrogen bonding. Thermal behavior and stability of crystal were studied using thermo gravimetric (TG) and differential thermal analyses (DTA) techniques. The second harmonic generation (SHG) of the material was confirmed using Nd: YAG laser. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)