Cation distributions estimated using the magnetic moments of the spinel ferrites Co_1-xCr_xFe₂O₄ at 10 K

(A)B₂O₄ ferrite samples with the composition Co_1-xCr_xFe₂O₄ (0.0 ≤ x ≤ 1.0) are prepared using a hydrothermal method, and subjected to calcining in a tube furnace with an argon-flow at 1673 K for 2 h. X-ray diffraction patterns indicate that each of all the samples has a single phase cubic spinel structure with a space group of Fd3 m. Magnetic measurements show that the saturation magnetization decreases with as the Cr content x increases. The cation distribution of the samples is estimated by fitting the dependence of the magnetic moments on x at 10 K, using the quantum mechanical model previously proposed by our group. The calculated sum of the content values of the Cr³⁺ and Cr²⁺ cations occupying the (A) sites increases as the value of x increases. In the fitting process, the magnetic moment directions of the Cr³⁺ and Cr²⁺ cations are assumed to be antiparallel to those of the Fe and Co cations, respectively, which is in accordance with Hund's rules.