On the effect of isovalent Bi substitution at the Eu site in the pyrochlore Eu2Ir2O7

Abstract

We investigate the structural and physical properties of the pyrochlores Eu2-xBi2xIr2O7 (x = 0, 0.05, 0.1, 0.25, 0.5, 0.75 and 1). We found that the lattice parameters of the compositions close to Eu2Ir2O7 end (i.e., x < 0.1) do not follow a regular increase as expected due the bigger ionic size of Bi3+ compared to Eu3+. Measurement of physical properties, including, resistivity and magnetic susceptibility showed a strong structure-property correlation in the x < 0.1 doping range. Above this doping level, the lattice parameters show a linear increase, and the physical behavior of the series quickly approaches that of the end member Bi2Ir2O7 which exhibits a metallic conductivity with no magnetic transition