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

Although the pure delafossite CuVO2 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 CuM1-xVxO2 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 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 Neel temperature larger than 4.5 K in the case of CuFe1-xVxO2 as determined from a Mossbauer study. (c) 2005 Elsevier SAS: All rights reserved.