Structure and hyperfine interactions of Bi9Ti3Fe5O27 multiferroic ceramic prepared by sintering and mechanical alloying methods

X-ray diffraction and Mِssbauer spectroscopy were applied as complementary methods to investigate the structure and hyperfine interactions in the Bi9Ti3Fe5O27 compound. Samples were synthesized by the solid-state sintering method at various temperatures as well as by mechanical alloying. An X-ray diffraction analysis proved that the sintered compounds formed single phases at a temperature above 993 K, while the mechanosynthesized material needed additional thermal treatment to complete the single phase formation. Mِssbauer studies confirmed the diffraction measurements. Compounds, both those prepared by a solid-state route and fired at 993 K and those mechanically alloyed contained residual hematite, however, those sintered at elevated temperatures and mechanically alloyed and subsequently annealed at 1173 K were single-phased materials. Room-temperature Mِssbauer spectra of the Bi9Ti3Fe5O27 compound revealed their paramagnetic properties suggesting that the Néel temperature of this ceramic was lower than room temperature.