Low-temperature synthesis of single-domain Sr-hexaferrite particles by solid-state reaction route

Sr-hexaferrite particles have been synthesized by conventional solid-state reaction route at low temperatures by boron addition that is used as an inhibitor for crystal growth. The effect of boron concentration on the structural, magnetic and electrical properties of Sr-hexaferrite particles are investigated by X-ray crystallography, scanning electron microscopy, magnetization and conductivity measurements. Saturation magnetization of Sr-hexaferrite increases up to 1?wt% boron addition, while coercivity becomes maximum with a boron amount of 2?wt%. Then, both magnetic parameters start to decrease with higher boron concentrations. Single-domain and single-phase powders have been obtained in the sample containing 1?wt% of boron that is sintered at 1050 degrees C. Impedance spectroscopies reveal that the dc conductivity increases tremendously with boron addition, while the ac conductivity increases with elevated temperature. The ac conductivity obeys roughly the power law of angular frequency in which tendencies change with temperature at low and medium temperature. Furthermore, higher contents of the dopant over approximately 2.0?wt% cause its temperature independency at higher frequencies. These are due to the grain size and secondary phase of hexaferrites that increases with the increase in boron amount. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim