Showing papers by "V. R. K. Murthy published in 2008"
TL;DR: In this article, structural and spectroscopic studies were carried out to understand the variation of dielectric properties with x. The symmetry of the compositions was determined to be monoclinic with space group P21/n, which corresponds to the a−a−c+ tilting system.
Abstract: The complex perovskite system (1−x)La(MgSn)0.5O3–xNd(MgSn)0.5O3 with the composition (x=0–1) was prepared by the solid state reaction method. Structural and spectroscopic studies were carried out to understand the variation of dielectric properties with x. Rietveld refinement was carried out with the initial model obtained by using the structure prediction and diagnostic software. The symmetry of the compositions was determined to be monoclinic with space group P21/n, which corresponds to the a−a−c+ tilting system, and the long-range order parameter was found to decrease with an increase in neodymium concentration. Raman spectra were analyzed by fitting the A1g-like mode to a Lorentzian peak shape. Intrinsic dielectric parameters were estimated by fitting infrared reflectance spectra with the four-parameter semiquantum model. Transverse optic phonon mode strengths and average phonon damping were calculated. The origin of increase in the intrinsic loss with the composition variation is discussed. Microwave...
32 citations
TL;DR: In this paper, the dielectric behavior of polar liquids like propionaldehyde, isopropyl amine and their equimolar binary mixture in nonpolar solvent benzene is studied in the microwave frequency range using the cavity perturbation technique at 6.218 GHz (J band), 9.880 GHz (X band), 16.331 GHz (P band) and 24.951 GHz (K band).
Abstract: The dielectric behaviour of the polar liquids like propionaldehyde, isopropyl amine and their equimolar binary mixture in nonpolar solvent benzene is studied in the microwave frequency range using the cavity perturbation technique at 6.218 GHz (J band), 9.880 GHz (X band), 16.331 GHz (P band) and 24.951 GHz (K band). Hamiltonian quantum mechanical calculations such as AM1, PM3, and MNDO optimized converged geometry operation is performed by using Argus lab chemical modelling software 2004 for both pure and binary systems of propionaldehyde and isopropyl amine. Dipole moments of the binary mixtures are calculated from the dielectric data using Higasi's method and compared with the theoretical results. Conformational analysis of the formation of a hydrogen bond between the propionaldehyde and isopropyl amine is supported by FT-IR, proton NMR spectra and molecular polarizability calculations. The average relaxation times are calculated from their respective Cole–Cole plots.
16 citations
TL;DR: In this article, the effect of Nb 5+ at the Ta 5+ site on the BMT structure was analyzed using the Rietveld technique on the X-ray powder diffraction data.
8 citations
TL;DR: The dielectric behavior of the polar liquids like propan-1-ol, isopropyl amine and their equimolar binary mixture in nonpolar solvent benzene is studied in the microwave frequency range using the cavity perturbation technique at 6.218 GHz (J band), 9.880 GHz (X band), 16.331 GHz (P band) and 24.951 GHz (K band) as discussed by the authors.
6 citations
Journal Article•
TL;DR: In this paper, the dielectric properties of glycine in aqueous solution medium in the microwave frequency region (130 MHz-20 GHz) are curried out using the open-ended coaxial probe technique.
Abstract: A study on the dielectric properties of glycine in aqueous solution medium in the microwave frequency region (130 MHz-20 GHz) is curried out using the open-ended coaxial probe technique. Dielectric parameters such as dielectric constant, dielectric loss of various weight percentage levels of glycine in double distilled aqueous medium such as water are determined. It is observed that the real part of dielectric permittivity decreases and imaginary part of the dielectric permittivity increases with increase in the weight percentage level of glycine in water. From these parameters we calculated the relaxation time and its behaviour is analysed. Dipole moment value is calculated from the optimized geometrical structure of the glycine molecule from the AM 1 , PM 3 , and MNDO ab initio quantum mechanical calculations using the Argus Lab chemical modeling Software 2004.
3 citations
TL;DR: In this article, the authors measured the mobility of polymer metal oxide composites with poly(methyl methacrylate) and metallic powders (CuO, Ni, and brushed Fe3O4) using a contactless microwave Hall effect technique with a bimodal cavity operating at 14 GHz.
Abstract: Films of polymer metal oxide composites with poly(methyl methacrylate) and metallic powders (CuO, Ni, and brushed Fe3O4) were prepared with a spin-casting method. Electric transport studies indicated that the compositions surpassed the percolation threshold limit. Alternating current (AC) conductivity studies confirmed a hopping mechanism with power-law behavior in frequency. For the first time, the mobility values of the carriers in these films were measured by the contactless microwave Hall effect technique with a bimodal cavity operating at 14 GHz. In this technique, a circular bimodal cavity is used to measure the change in the transmission coefficient (proportional to the carrier mobility) due to the application of a static magnetic field perpendicular to the microwave electric fields. The mobility measurements indicated a decrease in mobility with increasing quantity of CuO and Ni and showed an increase in the carrier–lattice scattering, whereas the mobility increased with increasing Fe3O4 due to the negative magneto resistance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
1 citations