LOW-TEMPERATURE PROPERTIES OF THE CUBIC K5R[NI(NO2)6]2 COMPOUNDS

The K5R[Ni(NO2)6]2 compounds are composed of interpenetrating bcc rare earth R3+ and fcc Ni2+ lattices, with overall Pn3 symmetry. The Ni - Ni interactions are antiferromagnetic but frustrated, as evidenced by the depressed ordering temperature of K5Y[Ni(NO2)6]2. The frustration appears to be reduced when certain of the rare earths are substituted for Y. Ferromagnetic order is observed for R = Gd at T(c) approximatel y 1.5 K. Susceptibility data for other R may be consistent with a spin glass ground state.