Study of cation magnetic moment directions in Cr (Co) doped nickel ferrites

Powder samples of the ferrites MxNi(1-x)Fe(2)O(4) (M = Cr, Co and 0.0 <= x <= 0.3) were prepared using a chemical co-precipitation method. X-ray diffraction analysis showed that the two series of samples had a single-phase cubic spinel structure. It was found that the magnetic moments (mu(exp)) per formula of samples measured at 10K decreased when Cr substituted for Ni, but increased when Co substituted for Ni, in spite of the fact that the magnetic moments of Cr2+ (4 mu(B)) and Co2+ (3 mu(B)) are higher than that of Ni2+ (2 mu(B)). With the assumption that the magnetic moments of Cr2+ and Cr3+ lie antiparallel to those of the Fe, Co, and Ni cations in the same sublattices of spinel ferrites, the dependences on the Cr (Co) doping level of the sample magnetic moments at 10K were fitted successfully, using the quantum-mechanical potential barrier model earlier proposed by our group. For the two series of samples, the fitted magnetic moments are close to the experimental results. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.