Crystal structures and magnetic properties of M2V2O7 (M=Co, Ni and Cu) compounds

Abstract The magnetic properties of M 2 V 2 O 7 (M=Co, Ni and Cu) have been investigated between 4 and 300 K. The results emphasize the relationships between the structural and physical properties of the titled compounds. M 2 V 2 O 7 (M=Co, Ni) exhibit a dichromate structure. The Ni-compound is antiferromagnetic, but the Co-one is ferromagnetic. Their specific heats confirm the low dimensionality at high temperature, and the magnetic transition is probably due to 3d–1d transition. The two varieties of Cu 2 V 2 O 7 compounds are type thortveitite. α-Cu 2 V 2 O 7 is an orthorhombic and β-Cu 2 V 2 O 7 is a monoclinic. The β-Cu 2 V 2 O 7 is an antiferromagnetic compound while α-Cu 2 V 2 O 7 is appraised as a ferromagnetic or canted antiferromagnetic one.