Papers by Author: M. Prema Rani

Abstract: Thermal conductivity of three different GaAs crystals, one grown by Liquid Encapsulated Czochralski technique and the other two samples grown by Vertical Bridgman technique have been experimentally measured at temperatures 310 K to 360 K. Two crystals are undoped and semi insulating and one crystal is conductive which is doped with Si and B(Silicon ≈ 4x1015 cm-3 and Boron ≈ 8x 1015cm-3). It has been experimentally observed that doping of silicon and boron gives rise to an increase in thermal conductivity.

Abstract: The alkali halide Na1-xAgxCl, with two different compositions (x = 0.03 and 0.10), was studied with regard to the Ag impurities in terms of the bonding and electron density distribution. X-ray single crystal data sets have been used for the purpose. The present analysis focused on the electron density distribution and hence the interaction between the atoms is clearly revealed by maximum entropy method (MEM) and multipole analyses. The bonding in these systems has been studied using two-dimensional MEM electron density maps on the (100) and (110) planes and onedimensional electron density profiles along the [100], [110] and [111] directions. The mid-bond electron densities between atoms in these systems are found to be 0.175 e/Å3 and 0.183 e/Å3, respectively, for Na0.97Ag0.03Cl and Na0.90Ag0.10Cl. Multipole analysis of the structure has been performed for these two systems, with respect to the expansion/contraction of the ion involved.