Delafossite oxides containing vanadium(III): Preparation and magnetic properties

Although the pure delafossite CuVO 2 does not exist, the present study well confirms that large amounts of vanadium(III) can be incorporated into copper based delafossites without reducing Cu + into metallic copper, as several solid solutions Cu M 1− x V x O 2 exist where M = Ga , Cr ( x ⩽ 0.50 ) or Fe ( x ⩽ 0.67 ). Vanadium(III) has a peculiar magnetic behavior. Actually V V antiferromagnetic interactions appear rather large at high temperature, but as the temperature decreases magnetic data can be (at least qualitatively) interpreted assuming the formation of V V pairs. The bonding involves one of the two electrons of the 3d 2 ( a 1 1 e 1 ) configuration of V(III)-atoms having a 6-fold D 3d coordination, the one occupying the e orbital that lies in the ( M, V) layers of the delafossite structure. The behavior changes from a rather 2D ferrimagnetic-like one to a 3D antiferromagnetic one with a Néel temperature larger than 4.5 K in the case of CuFe 1− x V x O 2 as determined from a Mössbauer study.