Structural and magnetic properties of Sr4–xMxIrO6(M = Ca, Zn, Cd, Li, Na)

Abstract

The compounds Sr_4–xCa_xIrO₆(x = 0.5, 1, 2, 3, 4) and Sr₃MIrO₆(M = Li, Na, Zn, Cd) have been synthesized and studied by X-ray powder diffraction and SQUID magnetometry. They all adopt the K₄CdCl₆ structure, with the cations M and Ca occupying only the trigonal prismatic sites in the [001] chains unless x > 1. Those compounds which contain only Ir^IV order antiferromagnetically at temperatures between 14 and 22 K, and those which contain only Ir^V show temperature-independent paramagnetism. The development of a self-consistent interatomic potential for the Ir^IV–O interaction is described. The lattice parameters predicted for the K₄CdCl₆-like phases using this new potential agree with the experimental values to within ca. 2%.