Magnetic susceptibility and powder neutron diffraction results are reported
on the cubic spinel Co2RuO4. These measurements indicate spin-glass format
ion in this compound, with a freezing temperature of about 16 K. Magnetic s
usceptibility results are also reported on ZnCoRuO4, a spinel in which only
the Ru3+ ions are magnetic. No magnetic order was found in ZnCoRuO4 down t
o 2 K, indicating extremely weak interactions between the octahedral Ru3+ i
ons in these materials. (C) 1999 Elsevier Science Ltd.