Ferromagnetism in a Mixture of Antiferromagnetic FeTiO3 and α-Fe2O3 as Observed by Using Mossbauer Spectroscopy

Ferromagnetism in a Mixture of Antiferromagnetic FeTiO3 and α-Fe2O3 as Observed by Using Mossbauer Spectroscopy

Solid solutions (1-x)FeTiO3-xFe2O3 of different compositions (x = 0.0, 0.1, 0.3, 0.5 and 1.0) were prepared by using a standard ceramic processing method and were studied by using X-ray diffraction, Mossbauer spectroscopy and vibrating sample magnetometer (VSM). The crystal sam- ples were found to have a rhombohedral structure. The lattice parameters (a and c) decreased linearly with increasing Fe concentration (x) and followed Vegard"s law approximately. For the sample with x = 0.1, the Mossbauer spectrum at room temperature was obtained by using the asymmetry two doublet corresponding to Fe2+ andFe3+. On the other hand, for the x = 0.3 and 0.5 samples, an anomalous six-line absorption curve was observed. The Mossbauer spectra at 4.5 K for the sample with x = 0.5 was fitted to three six-line hyperfine patterns with magnetic hyperfine fields of Hhf = 554.4, 528.4 and 438.5 kOe and isomer shifts of δ = 0.43, 0.59 and 0.89 mm/s. The values of the isomer shifts show that for all temperature ranges, the states are ferric (Fe3+) and ferrous(Fe2+). The slopes of the hyperfine magnetic fields depended on the temperature change at temperatures between 240 and 295 K, suggesting that a spin-rotation transition takes place. The Neel temperature and the Debye temperature were found to be 575 K and 355 K, respectively. The magnetic hysteresis curve measurements showed a ferromagnetic behavior at room temperature.

Solid solutions (1-x)FeTiO3-xFe2O3 of different compositions (x = 0.0, 0.1, 0.3, 0.5 and 1.0) were prepared by using a standard ceramic processing method and were studied by using X-ray diffraction, Mossbauer spectroscopy and vibrating sample magnetometer (VSM). The crystal sam- ples were found to have a rhombohedral structure. The lattice parameters (a and c) decreased linearly with increasing Fe concentration (x) and followed Vegard"s law approximately. For the sample with x = 0.1, the Mossbauer spectrum at room temperature was obtained by using the asymmetry two doublet corresponding to Fe2+ andFe3+. On the other hand, for the x = 0.3 and 0.5 samples, an anomalous six-line absorption curve was observed. The Mossbauer spectra at 4.5 K for the sample with x = 0.5 was fitted to three six-line hyperfine patterns with magnetic hyperfine fields of Hhf = 554.4, 528.4 and 438.5 kOe and isomer shifts of δ = 0.43, 0.59 and 0.89 mm/s. The values of the isomer shifts show that for all temperature ranges, the states are ferric (Fe3+) and ferrous(Fe2+). The slopes of the hyperfine magnetic fields depended on the temperature change at temperatures between 240 and 295 K, suggesting that a spin-rotation transition takes place. The Neel temperature and the Debye temperature were found to be 575 K and 355 K, respectively. The magnetic hysteresis curve measurements showed a ferromagnetic behavior at room temperature.