Crystal structures and magnetic properties of the high-pressure modifications of CoMoO4 and NiMoO4

The wolframite structure with β < 90° instead of β > 90° is observed for the high-pressure modifications of CoMoO4(II) and NiMoO4(II). Atomic parameters are reported as derived from X-ray powder diffraction with Rietveld refinement. Both compounds were prepared at a pressure of 50 kbar at 873 K from their α-phases. Antiferromagnetic ordering is observed below 68(1) K for CoMoO4(II) and 83(1) K for NiMoO4(II). At higher temperatures both compounds obey a Curie-Weiss law with Θ = − 125(5) K and |μ|(Co2+) = 5.4(1)μB for CoMoO4(II) and Θ = −145(5) K and |μ|(Ni2+) = 3.7(1)μB for NiMoO4(II).