Multifunctional GaFeO Obtained via Mechanochemical Activation Followed by Calcination of Equimolar Nano-System GaO-FeO.

The equimolar oxide mixture β-GaO-α-FeO was subjected to high-energy ball milling (HEBM) with the aim to obtain the nanoscaled GaFeO ortho-ferrite. X-ray diffraction, Fe Mössbauer spectroscopy, and transmission electron microscopy were used to evidence the phase structure and evolution of the equimolar nano-system β-GaO-α-FeO under mechanochemical activation, either as-prepared or followed by subsequent calcination. The mechanical activation was performed for 2 h to 12 h in normal atmosphere. After 12 h of HEBM, only nanoscaled (~20 nm) gallium-doped α-FeO was obtained. The GaFeO structure was obtained as single phase, merely after calcination at 950 °C for a couple of hours, of the sample being subjected to HEBM for 12 h. This temperature is 450 °C lower than used in the conventional solid phase reaction to obtain gallium orthoferrite. The optical and magnetic properties of representative nanoscaled samples, revealing their multifunctional character, were presented.