スピネル型ソフトフェライト(Ni_1-2xCa_xMg_x)Fe₂O₄ 及び (Mn_1-2xCa_xMg_x)Fe₂O₄ の研究

抄録

New spinel-type ferrites (Ni_1-2xCa_xMg_x)Fe₂O₄ and (Mn_1-2xCa_xMg_x)Fe₂O₄ (0 ≤ x ≤ 0.5) were synthesized using a solid-state reaction. The crystalographic parameters were determined by XRD. The ionic distributions were estimated from XRD and from the low temperature magnetization to be (Fe³⁺_0.875 Mg²⁺_0.125)[Ni²⁺_1-2xCa²⁺_xMg²⁺_x-0.125Fe³⁺_1.125]O^2-₄ (x ≥ 0.125) and (Mn²⁺_0.375-xFe³⁺_0.5+0.075xMg²⁺_0.125)[Ca²⁺_xMg²⁺_x-0.125Mn³⁺_0.5-xFe²⁺_0.5-xFe³⁺_1.125]O^2-₄ for the Ni- and Mn-system, respectively. Electrical resistivity ρ was remarkably increased by the substitution x. The maximum ρ at room temperature is 20 or 100 times of the non-substituted Ni-ferrite or Mn-ferrite, respectively