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Khandpekar M.M.,Material Research Laboratory | Pati S.P.,Sambalpur University
Journal of Crystal Growth | Year: 2010

Mixed transparent crystals of α-glycine, HCl and HF were obtained from saturated solution by slow evaporation technique. Relevant chemical and structural analysis has been carried out. The UV spectra shows the presence of a wide transparent window with an energy band gap of 6.21 eV and an SHG efficiency of 1.230 times of that of standard KDP crystal. Glacial acetic acid and water act as universal dislocation agents producing elongated pits on all cleavage and habit faces. Thermal evaporation of the crystals on etching shows presence of domains, lines, shallow pits and glide bands. Micro hardness studies indicate work hardening coefficient of 4.86. © 2009 Elsevier B.V. All rights reserved.

Khandpekar M.M.,Material Research Laboratory | Pati S.P.,Sambalpur University
Optics Communications | Year: 2010

Well defined transparent single crystals of α-glycine-sulpho-nitrate (GLSN) were obtained by slow evaporation of the solvent at room temperature. The new GLSN system crystallises in to orthorhombic symmetry with an indicative change in cell parameters depending upon the composition. CHNS, EDAX and proton NMR and carbon NMR analysis confirm the chemical units in the crystal. Comparative analysis of FTIR and laser Raman Spectra confirm the functional groups in the molecule. The TGA and DTA studies show presence of a transition anomaly at 413 K supported by resistivity and dielectric measurements. UV studies indicate wide transparency window with SWG conversion efficiency of 0.029 times of that of KDP material suggesting its use in optoelectronic devices. The crystal acts as a light sensor and exhibits light dependent nature indicative of conduction due of hydrogen ions with formation of space charge. The GSN crystal acts as a stable dielectric with a safe operating range of 300 volts/cm. © 2010 Elsevier B.V. All rights reserved.

Hankare P.P.,Shivaji University | Sanadi K.R.,Shivaji University | Garadkar K.M.,Shivaji University | Patil D.R.,Material Research Laboratory | Mulla I.S.,CSIR - Central Electrochemical Research Institute
Journal of Alloys and Compounds | Year: 2013

Nanocrystalline Co1-xNixFe 2O4 (where x = 0.0, 0.25, 0.50, 0.75, 1) were successfully synthesized by sol-gel method using citrate-nitrate precursors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were effectively utilized to investigate the different structural parameters. XRD showed single cubic spinel phase for all the samples. The decrease in lattice parameter and increase in crystallite size of the ferrispinel was observed with increasing nickel content. The surface morphology and elemental composition were studied by Scanning electron microscope (SEM) and Energy Dispersive X-ray analysis (EDAX) respectively. The nanosize of the synthesized material had been identified by TEM investigation and which is lies in between 20-25 nm. The semiconducting nature of the samples was studied by variation of resistivity and thermal emf with temperature. © 2012 Elsevier B.V. All rights reserved.

Khandpekar M.M.,Material Research Laboratory | Pati S.P.,Sambalpur University
Optics Communications | Year: 2012

Glycine sodium nitrite (GSNi) having non linear optical efficiency more than KDP crystal has been obtained from solutions by slow cooling technique. The crystals are found to be chemically and thermally stable with orthorhombic unit cell. The presence of wide transparency window in UV-Visible region makes GSNi suitable for opto-electronic device applications. It has second harmonic generation efficiency of 1.273 times that of standard KDP crystal. GSNi crystal belongs to soft category of materials with work hardening index of 2.33. Crystals introduced in timer circuit gave a stable output with the capacitance value of 236 pF. I-V characteristic indicates a safe operating range of 300 V/cm. GSNi is seen to behave as a normal dielectric with applied frequency and crystals exposed to light exhibit negative LDR characteristic which is attributable to space charge formation. © 2011 Elsevier B.V. All rights reserved.

Khandpekar M.M.,Material Research Laboratory | Pati S.P.,Sambalpur University
Optics Communications | Year: 2011

New trapezoidal, non-linear optical crystals of glycine potassium nitrate (GPN) have been grown by slow cooling from solutions with an initial pH of 4.3. Chemical composition, phase formation and functional groups have been verified by CHN, EDAX, XRF, NMR, XRD, FTIR and Raman studies. UV studies show a much lower cut off wavelength (195 nm) compared to the much investigated glycine sodium nitrate (GSN). The powder SHG efficiency of GPN is found to be 0.6 times compared to that of potassium dihydrogen phosphate (KDP). Cut and polished crystals exposed to light indicate positive photoconductivity. Electrical conductivity studies show an activation energy of 0.16 eV and the dielectric loss is found to decay drastically at higher frequencies (1 MHz) which is desirable in electronic applications. Vickers microhardness studies indicate a Mayer's index value of 2.78. Well resolved, elongated and oriented etch pits have been observed on the side habit face (220) treated in glacial acetic acid for 5 s. Typical circular features resisting the formation of etch pits representing impurity elements have been observed on the cleavage faces. Moisture has been traced on the surface of the crystals subjected to heat treatment. © 2010 Elsevier B.V. All rights reserved.

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