Structural characterization and magnetic properties of divanadates ZnMV2O7 (M = Co, Ni and Cu)

Divanadates of general formula ZnMV2O, (M = Co, Ni and Cu) have been prepared as powdered samples and the X-ray structural determination and magnetic studies have been carried out. Both ZnCoV2O7 and ZnNiV2O7 crystallize with the so-called dichromate structure type, showing monoclinic symmetry, space group P21 /c, while the third member of this family of vanadates ZnCuV2O7 shows the thortveitite structure type with monoclinic symmetry, space group C2/c. Magnetic susceptibility and specific heat measurements reveal that these derivatives behave as antiferromagnets and the estimated Neel temperatures are 4.5, 3.5 and 5.3 K for cobalt, nickel and copper vanadates, respectively. In all cases, the one-dimensional magnetic behavior that present the M,V2O7 vanadates is broken down when the magnetic cation M is half replaced by the diamagnetic Zn2+ to give the ZnMV2O7 samples studied in the present work.