Syntheses, crystal structures and magnetic properties of Rb 2RuO4 and K2RuO4

Abstract

Potassium and rubidium oxoruthenates, A2RuO4, were synthesized from the alkali peroxides/hyperoxides and ruthenium dioxide. Both compounds crystallize in the orthorhombic space group Pnma (no. 62), (K 2RuO4: a = 7.673(2), b = 6.153(2) and c = 10.564(3) Å, Z = 4,796 unique reflections, R = 3.5%; Rb2RuO4: a = 8.106(2), b = 6.270(1) and c = 11.039(2) Å, Z = 4,889 unique reflections, R = 3.6%). The crystal structures, as determined from single crystal data, are of the β-K2SO4 type. Magnetic measurements reveal that both compounds are paramagnetic down to temperatures of around 60 K and further exhibit antiferromagnetic transitions, at around T N = 9 K for Rb2RuO4, and two transitions with TN = 14 K and 4 K for K2RuO4. The magnetic moments as determined applying Curie-Weiss law for both compounds are 2.68 μB, thus confirming the oxidation state +6 of ruthenium. © 2005 Verlag der Zeitschrift für Naturforschung.