Production of single-domain powders of europium iron garnet using supercritical fluid technology

Abstract

• Controlled size powders of Eu 3 Fe 5 O 12 were obtained using SAS method; • Thermal decomposition stages of the obtained garnet precursors were considered; • Critical grain size for the transition to the single-domain state is 33 nm. In this work, nanosized precursors of the Eu 3 Fe 5 O 12 complex oxide – europium iron garnet – were prepared for the first time by the method of a supercritical antisolvent precipitation. It was shown that changing the synthesis parameters, namely, pressure, temperature, concentration of the initial solution and nozzle diameter, made it possible to obtain particles of controlled size from 20 to 80 nm. The obtained samples were characterized by a complex of physicochemical methods of analysis: IR spectroscopy, XRD, TG/DSC analysis, TEM. The main magnetic characteristics were obtained from powders annealed at 800 °C on a vibration magnetometer. The dependence of the magnetic characteristics on the grain size was established. The critical size of the transition to the single-domain state is 33 nm. The features of the garnet crystalline phase formation for samples with the smallest grain size and extended surface were revealed.