Neutron Diffraction Study of the ZnFe2-xCrxO4 Series

ZnFe2-xCrO4 spinels with x = 0, 0.1, 0.5, 1.0, 1.5, 1.9, and 2.0 were investigated. The lattice and the oxygen parameter were determined by means of X-ray and of neutron diffraction methods, The neutron diffraction pattern at T = 4.2 degrees K for a compound with x = 0.1 is similar to those of ZnFe2O4. For 0.5 <= x < 1.5 short-range magnetic order is observed at low temperatures. A detailed analysis of the magnetic structure of the compound with x = 1.9 is performed. The magnetic unit cell is 2 a, 2 a, 2 a and the spin arrangement as for MgCr2O4. The Neel temperature is T-N = 16 degrees K and the magnetic moment of the Cr3+ ion is equal to 2.4 mu(B).