Crystal Research

Crystals of potassium hydrogen phthalate (KAP), a semi-organic compound, have been grown by slow evaporation method at room temperature from aqueous solution in the presence of mono valent metal ionic impurities Ag+, Li+ and Na+. Elemental analysis by inductively coupled plasma optical emission spectroscopy (ICP-OES) proves the incorporation of these impurities into the grown crystals. Powder X-ray diffraction studies confirmed the phase formation and metal ions doping into KAP crystals. Thermo gravimetric analysis (TGA) show the onset decomposition temperatures to be 255, 258, 238 and 272°C for pure and Ag+, Li+ and Na+ doped KAP crystals respectively. Microhardness studies revealed that Na-KAP crystals have higher hardness values than all the doped crystal. All the crystal exhibited the second harmonic generation (SHG) conversion efficiency. The grown crystals were also subjected to Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy studies and dielectric studies. Among the three investigated metal ion impurities, Na+ ion seem to have positive influence on the growth, mechanical, thermal, dielectric and SHG characteristics of KAP which makes it suitable for limited level of applications.

Optical quality single crystal of Piperazine di-orthophosphate (PDOP) has been synthesized and grown by slow evaporation solution growth technique. Single crystal X-ray diffraction study reveals that the crystal belongs to triclinic system with space group P-1. The powder X-ray diffraction spectrum was recorded and the peaks were indexed. UV-Vis 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. Thermal analysis carried out on the compound reveals that the sample is stable upto 160º C. The second harmonic generation efficiency of the title material is 0.85 times higher than that of the standard KDP crystal.

The thin films of Ni-Phthalocyanine Tetrasulfonic acid tetrasodium salt and poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (NiPcTs:PEDOT:PSS) blend with different (PEDOT:PSS) concentrations (0.5 ,1, 2) on glass substrates were prepared by spin coating at thickness (100 nm). The structure and surface morphology of films were studied using X-ray diffraction , atomic force microscope (AFM),Scanning Electron Microscope (SEM),and showed that there was a change and enhance in the crystallinity. Analysis of X-rays diffraction patterns of NiPc in powder form structure is polycrystalline and display a strong reflection at (100) orientation. Another peak distinguished in the XRD pattern of as-deposited which represents a reflection at (102) orientation and grain size increased with increasing (PEDOT:PSS) ,This result was supported by AFM measurements, which exhibited a larger grain size. While (SEM)is observed that the shapes of grain is fiber to nanofiber with increasing PEDOT:PSS concentration .

Single crystals of potassium acid phthalate (KAP), a semi organic crystal have been grown from aqueous solution by slow evaporation technique by adding non essential, semi essential and essential amino acids L-cystine (CY), histidine (HI) and L-lysine(LY) as additives. Powder X-ray diffraction studies confirmed the phase formation and amino acids doping into KAP crystals. Optical absorption studies reveal that all the doped crystals possess higher absorption of visible ray than pure KAP crystals. Optical transmission is found to be low in case of LY doped KAP than all the other crystals. TG-DTA studies show the onset decomposition temperatures to be 255, 260, 247 and 230?C for pure, CY, HI and LY doped KAP crystals respectively. All crystals show SHG efficiency. 8.6mV, 6.8mV, 8.6mV and 5.5mV for (28mV for KDP) pure, CY, HI and LY doped KAP crystal. Grown crystals were subjected to FTIR, microhardness and dielectric studies. Key words: A. Optical materials; B. Crystal growth; C. Infrared spectroscopy; C. Thermo gravimetric analysis (TGA); C. X-ray diffraction; D. Dielectric properties; E. NLO and microhardness. a*Corresponding author:Email: wkum62@gmail.com,Tel: + 91 9566891852,

We have reformulated equations of state (EOS) for superconductors based on Lagrangian and Eulerian strains following the method developed by Stacey. The expressions thus obtained are used conveniently to assess the validity of various EOS for different types of superconductors. The logarithmic EOS based on the Hencky measure of finite-strain is also modified by including the higher terms arising from the fourth-order contribution in the Taylor series expansion of the free energy. In the present work, pressure of five different superconductors viz. YBa2Cu3O6.6, YBa2Cu3O6.93, YBa2Cu3O7, Bi2Sr2CaCu2O8 and Nd1.32Sr0.41Ce0.27CuO3.96 has been computed at different compression ranges using five different EOS based on finite strain theory viz. Third order Eulerian EOS, Third order Lagrangian EOS, Second order Born-Mie EOS, Third order Born-Mie EOS and Bardeen EOS. the obtained results are compared with available experimental data to test the validity and success of these equation of states.

Triglycine Sulphate (TGS) is an important material used in the fabrication of high sensitivity infrared detectors at room temperature. Single crystals of TGS were grown by solution method with slow evaporation and water as solvent at room temperature. The grown crystals were characterized by XRD analysis. It is found to exhibit monoclinic structure with the space group P21. The chemical composition of triglycine sulphate crystal was confirmed by Energy Dispersive X-ray Analysis (EDAX). The Refractive index was calculated as 1.534 by using Brewster’s angle method. UV-Visible spectra showed that the grown crystals have wide optical transparency in the entire visible region.

Pure and divalent metal ion Mg 2+ doped Copper sulphate and Potassium Dichromate crystals have been grown from aqueous solution by slow evaporation technique. The pure copper sulphate and pure potassium dichromate crystals were noted as CUS and KDC. Powder X-ray diffraction studies confirmed the phase formation and magnesium ions doping into KAP crystals. The presence of functional groups in the crystal has been observed by FTIR analysis. Optical transmission studies were carried out by allowing the UV-Vis ray of wavelength between 200 and 1100 nm was pass through the (010) face of the grown crystals. The optical transmission studies reveal that the pure and magnesium ion doped copper sulphate crystals were better transmission in the wave length region of 350 nm to 550 nm. In the case of pure and doped potassium dichromate crystals transmission was better in the wavelength region of 550 nm to 1100 nm. Optical transmission is found to be decreases in pure and magnesium ion doped copper sulphate crystals from 550 nm to 800 nm and above 800 nm it was increases up to 1100 nm.SHG efficiency of all these crystals were not active. The grown crystals were also subjected to FTIR and microhardness studies.

Lithium sulphate doped urea thiourea crystals were grown by slow evaporation method at 30 °C. The method of growing 1:3:2 UTLS crystals is explained. The structural studies on the grown crystals were carried out by X-ray diffraction analysis. The grown crystals are found to be in orthorhombic structure and the lattice parameters of pure urea thiourea crystal are a =7.657 Å, b = 8.588 Å and c= 5.485 Å. The lattice parameter is distorted due to the incorporation of lithium ion into the lattice sites of the urea thiourea crystal. The functional groups of the grown crystals have been identified by the Fourier Transform Infrared Spectroscopy. Optical transmittance and thermal stability of the materials were carried out by UV-Vis-NIR and TG/DTA analysis. The nonlinear nature of the crystal is confirmed by SHG test.

Good quality single crystals of pure p-hydroxy acetophenone (PHAP) and Cd+ doped p-hydroxy acetophenone have been successfully grown from aqueous solution by slow evaporation technique. The lattice parameters of these crystals are found to be for pure PHAP and Cd+ doped PHAP using X-ray diffraction method. The functional groups of the materials are confirmed qualitatively by FTIR spectral analysis. Optical absorption studies on these samples reveal the minimum absorption region to be well suited for NLO applications. Thermal analysis have been carried out on the compounds confirm the samples are thermal stable up to 163ºC.

 The search for new NLO materials is a never ending process. Good quality Aluminium Nitrate doped Sulphamic Acid single crystals have been grown by slow evaporation technique. The unit cell parameters of the grown crystals were studied using single crystal XRD. The functional groups present in the grown crystal were identified by FTIR analysis. Optical behaviour of the grown crystal was investigated using UV-Vis-NIR studies. The thermal stability of the grown crystal was confirmed by Thermogravimetric analysis (TGA)/Differential thermogravimetric analysis (DTA).The mechanical strength and Nonlinear optical property of the crystal were determined by Vicker’s Microhardness Test and Kurtz powder technique respectively.Nonlinear optical property of the crystal were determined by Vicker’s Microhardness Test and Kurtz powder technique respectively.