Low-temperature Mössbauer study of the MgCd ferrite system

Samples of the magnesium-cadmium ferrite series Cd_xMg_1?xFe₂O₄ (X = 0 to 0.8) have been studied by the Mössbauer-effect technique at 4.2 K. Mössbauer spectra for X = 0.0 to 0.8 suggest the existence of two hyperfine fields, one due to the Fe³⁺ tetrahedral ions (A-sites) and the other due to Fe³⁺ octahedral ions (B-sites). The systematic dependence of the isomer shifts, quadropole interactions and nuclear magnetic fields of ⁵⁷Fe³⁺ ions in both A- and B-sites has been determined as a function of cadmium content. The variations in the isomer shifts with Cd content are consistent with the variations in the Fe³⁺ -O^-₂ internuclear separations. It has been found here that supertransferred hyperfine interactions do not contribute to the systematics of the A- and B-site hyperfine fields.