SR4-XCAXRHO6 - A MAGNETICALLY ORDERED RH-IV COMPOUND

Sr4-xCaxRhO6 (x=0,1) has been prepared at ambient pressure using the standard techniques of solid-state chemistry. Profile analysis of the X-ray powder diffraction (XRPD) data shows that the rhombohedral product is isostructural with Sr4IrO6. It thus contains Rh-IV cations in octahedral sites and alkaline-earth-metal cations in trigonal prismatic coordination. The mean Rh-O distance is 2.04 Angstrom. Both of the compositions studied order antiferromagnetically at ca. 7 K. The magnetic susceptibility data have been analysed using both a Curie-Weiss Law (mu(eff)(300 K)=2.03 mu(B) for x=0) and the one dimensional (1D) Ising model [J/k=-3.30(1) K for x=0].