Optical, thermal, dielectric and mechanical studies on glycine doped potassium dihydrogen orthophosphate singles crystals grown by SR method (original) (raw)
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Optical Materials, 2013
Glycine added potassium dihydrogen phosphate (KDP) crystals have been grown by slow evaporation solution technique, slow cooling along with seed rotation and Sankaranaryanan-Ramasamy (SR) method. The size of the grown crystal in slow cooling method was 35 Â 25 Â 20 mm 3 and in SR method it was 20 mm in diameter and 110 mm in length. The grown crystals were subjected to powder X-ray diffraction, UV-Vis, thermal analysis, Vickers microhardness, dielectric, laser damage threshold, higher resolution X-ray diffraction (HRXRD) and nonlinear optical (NLO) studies. All the grown crystals have good transparency in the entire visible region. In order to determine mechanical strength of crystal, Vickers micro-hardness measurement was carried out. Dielectric study reveals higher dielectric constant and low dielectric loss for SR method grown crystal. High laser damage threshold was observed in SR method grown glycine added KDP crystal compared to SR method grown pure KDP crystal. The second harmonic efficiency of the glycine added KDP is increased compared to pure KDP.
Transparent single crystals of potassium dihydrogen phosphate (KDP) were grown by modified Sankaranarayanan–Ramasamy (SR) method. The band gap energy for the KDP crystals was calculated from optical transmission spectrum. The theoretical calculations to determine the optical constants of the material and a technique for photonic band gap tuning, which is essentially required to develop the optoelectronic devices, were determined using the optical studies. Further, the Vicker's micro hardness as well as parameters such as fracture toughness (K c), brittleness index (B) and yield strength (s v) are presented.
Journal of Crystal Growth, 2011
Single crystals of pure, L-arginine and glycine doped ammonium dihydrogen orthophosphate (ADP) were grown by both the slow solvent evaporation method and the temperature-gradient method of Sankaranarayanan-Ramasamy (SR). The metastable zone width for different saturation temperatures of pure glycine and L-arginine added solutions were carried out. The grown crystals were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), optical transmission, dielectric constant, dielectric loss, and Vickers microhardness. The DSC and TG curves of the grown crystals indicated that they were stable up to 200 1C. The XRD study confirmed the structure of the grown crystal. The optical transmission analysis revealed that the pure and doped ADP crystals had very high percentage of transmission in the entire visible region. The important optical parameters such as reflectance and extinction coefficients of the grown crystals were calculated. L-arginine and glycine were used as dopants to reduce dielectric constant of ADP. The a.c. resistivity and a.c. conductivity were calculated. Dielectric loss of the doped ADP crystals grown by the SR method is lower than the doped ADP crystals grown by the conventional method. Larger hardness value for the SR method grown crystals confirmed greater crystalline perfection.
The Praseodymium doped potassium dihydrogen orthophosphate (KDP) crystals were grown from aqueous solution by the temperature lowering method using a microcontroller based seed rotation technique and slow evaporation technique with the vision to improve the properties of the crystal. The chemical composition of the grown crystals is confirmed by EDAX Analysis. The grown crystal was characterized by PXRD analysis confirm the crystalline nature and shifts in peak positions due to doping is observed. Using Scherer\\\'s equation particle size has been calculated. Solubility of crystals grown by slow evaporation technique is determined. The solubility curve shows that praseodymium doped KDP crystals has higher solubility than the pure KDP. The SHG efficiency is determined by Kurtz powder technique. It is found that relative SHG conversion efficiency of crystal grown by Seed rotation technique is greater compared to other technique. The UV-Vis spectrum shows that percentage transmission of crystals grown by seed rotation technique is greater compared to slow evaporation. The electronic band transition is studied from the plot of (?hv)2 versus photon energy (hv) and the band gap energy has been calculated. The dielectric constant, dielectric loss and ac conductivity of the crystal were studied as a function of frequency and the results are discussed. The functional groups are identified by FT-Raman analysis. The Optical transmission and SHG studies shows the suitability of the ingot for optical applications.
Journal of Crystal Growth, 2008
Single crystals of potassium acid phthalate (KAP), a semi-organic compound, have been grown at an average growth rate of 4 mm/day from aqueous solution by using the uniaxial crystal growth method of Sankaranarayanan-Ramasamy (SR). Transparent, cylindrical KAP crystal of size 70 mm length and 15 mm diameter was grown. The grown crystals were characterized by etching and UV-vis NIR analysis. HRXRD analysis indicates that the crystalline perfection of SR method-grown KAP is good. The KAP crystals grown by SR method have 9% higher transmittance than conventional method-grown crystal. The microhardness test was carried out on the (0 1 0) face and a load-dependent hardness was observed. TG-DTA evaluated the thermal properties of the grown crystal. KAP was found to be thermally stable up to 290 1C. The dielectric constant and dielectric loss of the crystal were studied as function of frequency and temperature.
Journal of Crystallization Process and Technology, 2011
Pure potassium dihydrogen phosphate (KDP) crystals and KDP doped with L-alanine have been grown by slow evaporation technique at room temperature. Grown crystals have been characterized using powder X-ray diffraction, (XRD), Energy Dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared spectroscopy (FTIR). The presence of L-alanine into pure KDP crystal was confirmed by FTIR and EDX spectra. Crystal structure has been studied by XRD. Pure KDP and L-alanine doped KDP crystals both possessed tetragonal structure. The transparency is found to increase with the increase of doping concentrations of the grown crystals as observed by UV-Vis spectra. A.C. electrical conductivity of grown crystals along the growth axis was carried out at various temperatures ranging from 35˚C-400˚C. Dielectric constant and dielectric losses are measured as a function of temperature and this study reveals the contribution of space charge polarization. Crystal defects and surface morphology are studied by dissolution solvent technique and reveals the step growth mechanism for both pure and doped crystals.
Semi-organic single crystals of glycine potassium sulphate were synthesized by a slow evaporation technique. Good quality single crystals with size 6.02mm x 2.63mm x 1.81mm were grown in 32 days. Single crystal and powder XRD analyses confirmed the orthorhombic crystal structure. Vibration spectrum was recorded to determine the symmetries of molecular vibrations. The TGA, DTA shows that the material has good thermal stability; the UV-Vis spectrum shows the transmitting ability of the crystal in the entire visible region. The dielectric constant and dielectric loss were calculated by varying frequencies at different temperature. The microhardness test reveals that the crystals possess good mechanical strength.
Optical Materials, 2014
The effect of L-tyrosine doping on various properties of potassium dihydrogen phosphate single crystals grown by slow cooling along with seed rotation method has been investigated. The crystalline nature of the grown crystals has been analyzed by powder X-ray diffraction analysis. The presence of various functional groups is identified by Fourier transform spectroscopy. Optical transparency of the grown crystals has been analyzed by UV-Vis-NIR spectral analysis. 90% of transmittance was observed for L-tyrosine added potassium dihydrogen phosphate crystal. Thermal stability and micro hardness measurement was examined by TG-DTA and Vickers microhardness study. Second harmonic study was carried out using Kurtz and Perry method. Dielectric and laser damage threshold studies were carried out.
Crystal growth, thermal, optical, and dielectric properties of L-lysine doped KDP crystals
Potassium dihydrogen phosphate (KDP) is a well known nonlinear optical (NLO) material having different applications in electro-optics and laser technology. Pure and amino acid L-arginine doped KDP single crystals were grown by the slow solvent evaporation technique. The 0.3, 0.4 and 0.5 weight % doping of L-arginine was successfully achieved in KDP crystals and confirmed by paper chromatography, CHN analysis, FTIR and UV-Vis spectroscopies. The dielectric behaviour of the samples has been studied. The variation of dielectric constant, dielectric loss (tanδ), a.c. resistivity and a.c. conductivity with frequency of applied field in the range from 100 Hz to 100 kHz is reported. The effect of amino acid doping was observed on SHG efficiency. The results are discussed.