Magneto—Mössbauer Study of Cu0.5Fe2.5O4

Abstract

Saturation magnetization and Mössbauer measurements at different temperatures from 4.2° to 623°K have been made on samples of composition Cu_0.5Fe_2.5O₄ sintered at different temperatures between 1210° and 1350°C and quenched to room temperature. The Mössbauer spectra consist of a superposition of two six‐line patterns, which are attributed to iron on B sites and A sites, on the basis of the change in the intensity of the spectra with the substitution of a small amount of Sc in Cu_0.5Fe_2.5O₄. The relative isomer shifts and hyperfine fields also confirm this assignment. The internal magnetic field at the iron nucleus at 300°K is H^β = 473±2 kOe and H^A = 402±2kOe. The isomer shifts relative to metallic iron and the A and B sites are found to be characteristic of the iron in the trivalent state. The saturation magnetization, Curie temperature, and hyperfine fields are found to be practically independent of the sintering temperature. The ratio of the iron site occupancy factor is determined from the intensity ratio of the Lorentzian fits of the two patterns and is compared to the value deduced from magnetization measurements. The various models proposed for this system are discussed in the light of the present work.