Effect of Nb doping at Mn site on thermal expansion of Pr0.7Sr0.3MnO3

In this study we present results on effect of Nb doping on thermal expansion of Pr0.7Sr0.3MnO3. Thermal expansion measurements were done using three terminal capacitance method. The pure sample shows a jump at the insulator–metal (I-M) transition temperature, and with Nb doping, a fourfold decrease in the jump is found. Since thermal expansion is a bulk property, this suggests that the dopants are not in the form of local clusters; rather they are distributed uniformly throughout the sample. Temperature variation of Gruniesen ratio α/CP shows that for temperatures below I–M transition, the ratio is weakly dependent on temperature. Pressure dependence on the transition temperature, dTP/dP and jump in compressibility, Δβ, of these samples has been estimated using well-known Ehrenfest equations. The present results are in fairly good agreement with those reported in the literature.