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 vertical stroke μvertical stroke (Co2+)=5.4(1)μB for CoMoO4(II) and Θ=-145(5) K and vertical stroke μvertical stroke (Ni2+)=3.7(1)μB for NiMoO4(II). (orig.)