Structure and Magnetic Properties of Ni4V3O10, an Antiferromagnet with Three Types of Vanadium–Oxygen Polyhedra

The compound Ni4V3O10 forms a new structure type in the tetragonal space group P4/n. The material can be produced using solid-state synthesis in a narrow temperature range, and the structure was confirmed using X-ray and neutron powder diffraction data. The phase contains occupationally disordered Ni/V in regular-octahedral sites and V in tetrahedral and vanadyl-octahedral sites. Bond valence and neutron/X-ray co-refinement data are compatible with three vanadium oxidation states (V3+, V4+, V5+) existing in the material, which would make it distinct in the Ni–V–O system and would place it in a small class of oxides with transition metals exhibiting three oxidation states. With a Néel temperature of 38 K and a Curie–Weiss parameter θ = −234 K, it displays frustrated antiferromagnetism evidenced by a broad hump in the heat capacity below TN. The structure has a percolating distorted rock-salt-like network, leading to strong superexchange, but vanadyl-octahedral linkages frustrate magnetic ordering. The magnetic structure is assumed to be incommensurate, as simple propagation vectors can be ruled out by powder neutron diffraction.