Electrical and magnetic properties of γ-Fe 2O 3 synthesized from ferrous tartarate one and half hydrate

Abstract

Gamma ferric oxide (γ-Fe 2O 3) prepared from ferrous tartarate one and half hydrate has been investigated using dc electrical conductivity, the Seebeck coefficient, the X-ray diffraction pattern, the initial magnetization, magnetic hysteresis, Mössbauer spectroscopy and scanning electron microscopy. The study of the dc electrical conductivity of freshly prepared γ-Fe 2O 3 and that of a sample stored for seven days in static air suggests that γ-Fe 2O 3 absorbs oxygen and water from the atmosphere. The formation of a hydrogen ferrite phase is based on the kink in the log σ against T -1 curve observed at 185°C. The suggestion that the hydrogen ferrite phase is formed has been substantiated by comparison with the X-ray diffraction pattern and magnetic properties of γ-Fe 2O 3 heated under a nitrogen atmosphere. The γ-Fe 2O 3 to α-Fe 2O 3 transformation was observed using electrical conductivity and initial magnetization measurements; this magnetic study also established the single-domain character of γ-Fe 2O 3. The scanning electron microphotographs showed that the γ-Fe 2O 3 particles were acicular in shape and the Mössbauer spectrum showed a well-resolved six-band spectrum.