Crystal Research

Bulk single crystal of L-Valinium picrate (LVP) was successfully grown from aqueous solution by Sankaranarayanan -Ramasamy (SR) unidirectional growth method with dimensions of 12 mm diameter and 75 mm length. Single crystal X-ray diffraction studies and powder XRD analysis have been carried out to confirm the structure and perfection of the crystal. The optical absorption window and the cutoff wavelength of the LVP have been identified by UV–Vis–NIR studies. Photoluminescence studies indicate that the grown crystal has a green fluorescence emission. The mechanical asset of the grown crystal has been studied using Vicker’s microhardness tester. Dielectric studies have been carried out for the grown crystal and the results were discussed in detail.

The organo-metallic nonlinear optical material urea doped thiourea zinc sulphate (UTZS) has been successfully grown by slow evaporation method at constant temperature 30?C from its aqueous solutions. The grown crystals were subjected to powder x-ray diffraction to determine the unit cell parameters. The UV-Vis transmittance spectrum shows that the crystal has a good optical transmittance in the entire visible region with lower cutoff wavelength. The second harmonic generation efficiency was measured in comparison with KDP by employing powder Kurtz method. The vibrational frequencies of various functional groups in the crystals have been derived from FI-IR analysis. The thermal stability of the grown crystal was analysed by thermogravimetric (TGA) and differential thermal (DTA )analyses. The vicker’s hardness was carried out to test even distribution of load and to study the mechanical strength of the crystal. The dielectric response of the crystals was studied in the frequency range 100HZ-5MHZ at different temperatures and the results are discussed.

Benzoyl Glycine (BG) an organic nonlinear optical crystal was synthesized and grown by slow evaporation method at room temperature. Single crystal X-ray diffraction study reveals that the crystal belongs to orthorhombic system and crystallizes in the non centro symmetric space group P212121. Powder X-ray diffraction was recorded and the peaks were indexed. Absorption spectrum shows that the crystal is transparent in the entire visible region. The functional groups present in the material were interpreted by FTIR spectral analysis. TG-DTA was performed to study the thermal stability of the crystal. Microhardness and etching studies were also carried out. The SHG efficiency of BG was 2.5 times higher than that of KDP.

A new semi-organic crystal of L-Alanine oxalate monohydrate has been grown from saturated solution by slow evaporation technique at room temperature. The grown crystal was confirmed by X-ray diffraction. The vibrational frequencies of various functional groups in the crystals have been derived from FTIR analysis. A wide transparency window useful for optoelectronic applications is indicated by the UV studies. The thermal behavior of the crystals has been investigated by TG/DTA analyses. The mechanical strength of the grown crystals was estimated by using Vicker’s microhardness tester. Second Harmonic Generation (SHG) efficiency of the powdered material of L-Alanine oxalate monohydrate (LAOM) tested by using Kurtz method.

The title compound of C2H5NO2•Ba (NO3) Glycine Barium Nitrate (GBN), a semiorganic glycine additive material has been grown from slow evaporation solution growth technique at room temperature.. The grown single crystals have been analyzed by powder crystal X-ray diffraction. The title compound has good optical transmission in the entire visible region. The optical band gap has been estimated using Tauc’s plot. Its relative SHG efficiency has been tested by Kurtz powder method and it quite interesting that it acts as poison, not favoring NLO efficiency. Thermal stability of the grown crystal was investigated by thermo gravimetric and differential thermal analyses.

Zinc oxide nanoparticles doped with Vanadium of varying concentrations were synthesised by Sol-gel method. Samples prepared after annealing for 2 hrs at 600 oC are characterised by XRD,UV-Vis Spectroscopy, SEM and EDS. The hexagonal wurtzite structure is maintained in ZnO after vanadium doping at high concentration (15 at.%) as confirmed by X-ray analysis. The absorption edge of ZnO is red shifted by increasing the vanadium concentration. SEM shows the nanoparticle nature of the ZnO particle, molar concentration of dopants is confirmed by EDS analysis. The photo catalytic activity of Rhodamine-B dye solution under visible light is better for V-doped ZnO as compared to pure ZnO.

Single crystals of 2-methyl-6-nitroaniline of reasonable size and excellent quality were grown by the low-temperature solution growth method using methanol as a solvent. Supersaturation was established by lowering the temperature at a rate of 0.2°C/hr. The powder XRD of the samples suggested no significant change in the unit cell dimensions and the presence of any extra phase. The structural analysis and infrared spectroscopy can be useful in the clarification of the role of hydrogen bonds in crystals exhibiting non-linear optical properties. It has found that these crystals have transparency from UV to Far-IR wavelength region. Powder Kurtz-Perry measurements were performed for the investigated material. The efficiency of second order susceptibility was estimated relative to urea: deff = 8 urea. The dependence of the birefringence of the investigated crystal was studied with respect to the applied dc field and the results were discussed.

Diglycine hydrobromide an intriguing material for frequency conversion has been grown by slow evaporation solution growth technique at room temperature. Their structural, optical and physicochemical properties were characterized by X-ray powder diffraction and UV-Vis spectra. The title crystal has found to crystallize into noncentrosymmetric orthorhombic P212121 space group. The material has a wide transparency in the entire visible region. It is found that the cutoff wavelength lies in the UV region. The dielectric studies were carried out using the instrument, N4L LCR meter. The compound is a prospective crystalline material for second order nonlinear optical application.

High quality bulk single crystal of L-arginine phosphate (LAP) was grown by slow evaporation which is based on temperature reduction method. L-arginine phosphate (LAP) seed crystals were grown at pH value of 5.8 at 30⁰ C by slow evaporation technique around 12 days and the bulk crystal was grown by Mason-jar method for 20 days. The grown crystals were subjected to optical and morphological studies. The unit cell parameters were calculated by X- ray diffraction. The UV-Vis spectrum shows the transmitting ability of the crystals in the entire visible region and the transmittance percentage is increased for the LAP crystals. The presence of the functional groups was identified by FT-IR spectrum. Hence L-arginine crystals are found to be more beneficial from an application point of view as compared to KDP crystals. From Micro hardness test the mechanical strength of the crystal has been observed.

An organic nonlinear optical crystal of Cesium Sulfamate crystal has been synthesised and grown by the slow evaporation solution growth method. Single crystals of optical quality were obtained by slow evaporation technique. The grown crystals were characterised by powder XRD, UV-visible spectroscopy, DTA analysis and SHG measurement test. The SHG efficiency of crystal is greater than urea and transmittance cut off wavelength is 424nm. Hyperpolarizability analysis of Cesium Sulfamate were performed with the help of Density Functional Theory (DFT) calculations using Gaussian 03 software.