Structural, magnetic and electrical properties in the pyrochlore oxide Bi2-xCaxIr2O7-δ

Bi2-xCaxIr2O7-delta (x=0, 0.1, 0.2, 0.3, and 0.4) pyrochlore iridates were prepared by the solid-state reaction method in air. In this paper we reported a systematic study of hole-doped Bi2-xCaxIr2O7-delta by performing crystal structure, electrical transport and magnetic measurements. A high-crystallized Bi2-xCaxIr2O7-delta with a cubic structure was obtained. Because Bi3+ was substituted in a random way by Ca2+ which has relatively smaller ionic radius, disorder and phononic oscillations were induced and the the length of Ir-O bands were reduced. The doped samples were found to exhibit metal insulator transition. Magnetic measurements on the doping samples indicated a shift towards nonmagnetic Ir5+, and the anti-ferromagnetism was weakened. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.