Structural, microstructure and magnetic properties of strontium hexaferrite particles synthesised by modified coprecipitation method

摘要

Strontium hexaferrite (SrFe_(12)O_(19)) particles were synthesised using the modified chemical coprecipitation method. The results indicated that a single strontium hexaferrite phase formed at low annealing temperature 800°C in the presence of surfactant or by oxalic acid addition. Sonochemical assisted coprecipitation route improved the formation of well crystalline strontium hexaferrite phase with Fe~(3+)/Sr~(2+) molar ratios of 9-23 and 8 annealed at 1000°C for 2 h. The crystallite size of the produced powders increased with increasing annealing temperature. The crystallite size of the formed powders was in the range between 67 and 125 nm. The microstructures of the formed particles appeared as a hexagonal platelet-like structure. Moreover, the addition of surfactant exhibited a uniform homogeneous hexagonal platelet-like structure. The formed ultrafine pure SrFe_(12)O_(19) powders have good magnetic saturations (44-6-73-6 emu g~(-1)) and wide intrinsic coercivities (692-5612 Oe).