Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Condensed Matter Physics 119show that the compound form in a well defined cubic pervoskite like structure. Unlike the case ofGdPd 3 B x C 1−x where one can tune the lattice parameter of the compounds, the lattice parametersFig.4.1.1.30of Ce 0.5 Eu 0.5 Pd 3 B x monitor a sharp jump and could not be tuned. This sharp jump in latticeparameter results from the change in the valency of rare-earth ions. It was argued earlier that thechange in the valency and occurrence of valence fluctuating states of Ce and Eu in CePd 3 B x andEuPd 3 B x respectively is an outcome of alteration in the lattice parameter or boron distributionin the lattice. However, our results show that Ce 0.5 Eu 0.5 Pd 3 , which has similar value of latticeparameter to EuPd 3 B x and which does not contain any boron in the lattice, exhibits the presenceof mixed valence states of Eu.Abhishek Pandey, C Mazumdar, R Ranganathan, S Dattagupta†, VR Reddy†, A Gupta†ECMP4.1.1.31 Study of transport and magnetic properties of GdPd 3 B−xC 1−x (x=0-1)Perovskite samples having general formula AIB 3 are being studied for quite some time for theirinteresting physical properties. These compounds form in cubic structures (space group Pm3m),where A atoms occupy cube corners, I atoms are in body center positions, and B atoms are in facecentered positions. We have studied temperature dependent resistivity and magnetic behaviour andstructural evaluation in GdPd 3 B x C 1−x series of compounds that form in this structure. We haveshown that by modifying the structural parameters and chemical environment of these compounds,the temperature coefficient of resistivity (TCR) can be controlled very smoothly over a wide range.