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Showing papers by "V. R. K. Murthy published in 2000"


Journal ArticleDOI
TL;DR: In this paper, solid solutions in the series Pb(Zr 0.53 Ti 0.47)O3 which belong to ABO3 type compounds were studied using the X-ray Rietveld technique from the tetragonal PbTiO3 end to the morphotropic phase boundary.
Abstract: Solid solutions in the series Pb(Zr x Ti1-x )O3 which belong to ABO3 type compounds were studied using the X-ray Rietveld technique from the tetragonal PbTiO3 end to Pb(Zr0.53 Ti0.47)O3 which is near the morphotropic phase boundary. A systematic structure analysis carried out for this series revealed that tetragonal and rhombohedral phases coexist even when Zr/Ti ratio is 40/60. Quantitative phase analysis using Rietveld method has been carried out for compositions falling in the two phase region. Substantial decrease in distortions of the BO6 octahedra has been observed for the compositions near the morphotropic phase boundary.

62 citations


Journal ArticleDOI
TL;DR: In this article, the effect of the tilting of octahedra on polar phonon modes of lattice vibration was investigated, which contributes a major part to the dielectric polarization in the crystal.
Abstract: The aim of this work is to understand the effect of the tilting of octahedra on polar phonon modes of lattice vibration, which contributes a major part to the dielectric polarization in the crystal. The tolerance factor, which is a measure of the packing of ions in the perovskite unit cell, determines the tilting of oxygen octahedra in the perovskite materials. In this work we have discussed the variation of polar phonon frequencies with respect to the tolerance factor in the composition (Ba(1−x)Srx)(Zn1/3Ta2/3)O3 with x=0.0,0.3,0.5,0.7,1.0. The dielectric properties measured at the microwave frequency range are also highlighted to support the ideas proposed in this paper.

15 citations


Journal ArticleDOI
TL;DR: In this article, a new liquid crystal, 4-cyanophenyl 4-pentylbenzoate at and above the nematic-isotropic phase transition temperature, was reported.
Abstract: Measurements are reported for the d.c. Kerr response and the pretransitional behaviour of a new liquid crystal, 4-cyanophenyl 4-pentylbenzoate at and above the nematic-isotropic phase transition temperature. The real parts of the third order nonlinear susceptibilities chi(3) at and above the nematic-isotropic transition temperatures are determined for the new liquid crystal from the electro-optic Kerr effect (EOKE) experiments. The variation of the Kerr constant with temperature is discussed on the basis of the Landau-de Gennes model of the nematic-isotropic phase transition. The susceptibility values are also compared with that of the well known liquid crystal 4'-pentyl-4-cyanobiphenyl (5CB). The effect of the linking group of the liquid crystal on the suceptibility value is also discussed.

13 citations


Journal ArticleDOI
TL;DR: In this article, core and valence level spectra of (Sm 0.50Ca0.50)MnO3 are reported. The spectral weight of the valence band has a peak 6 eV below Fermi level.
Abstract: Core and valence level spectra of (Sm0.50Ca0.50)MnO3 are reported. The spectral weight of the valence band has a peak 6 eV below Fermi level. Comparative analysis with the similar class of compounds suggests that width of the valence band is low for this compound. Semiconductor type behaviour of this compound is qualitatively predicted using the features of valence band and core level spectra.

1 citations