Room-temperature ferromagnetic properties and Mössbauer investigation of the 0.7FeTiO 3–0.3Fe 2O 3 solid solution

Abstract

The 0.7FeTiO 3–0.3Fe 2O 3 solid solution were prepared by slow cooling and quenching heat treatments and studied by X-ray diffraction, Mössbauer spectroscopy, and vibrating sample magnetometer (VSM). The crystal structure of samples were found to be rhombohedral structure with the lattice constants of the slow-cooled sample a=5.082 Å and c=13.945 Å, and those of the quenched sample a=5.085 Å and c=13.964 Å. Mössbauer spectra of two samples were taken at various temperatures ranging from 4.2 to 400 K and anomalous absorption curves are observed. Mössbauer spectra was fitted to three magnetic components correspond to Fe 3+ and Fe 2+ in A and B sublattices. At 4.2 K, the magnetic hyperfine fields were H hf=512, 481, and 309 kA/m for the slow-cooled sample and 512, 479, and 305 kA/m for the quenched sample, respectively. The Mössbauer spectra below the Néel temperature, T N, reveal line broadening accompanying relaxation effects and intensity ratio different from usual powder pattern, indicating preferred spin orientation. The Néel temperature, T N, was determined to be 380 K for the slow-cooled sample and 400 K for the quenched sample. The temperature dependence of the magnetization taken in zero-field-cooling (ZFC) and field-cooling (FC) condition of the slow-cooled and quenched samples exhibits the great irreversibility between ZFC and FC magnetization. Magnetization measurements have shown ferromagnetic hysteresis loops at room temperature.