Effect of sintering temperature on magnetic and electrical properties of nano-sized Co2W hexaferrites

Nano-sized and single phase W-type hexaferrite (BaCo2Fe16O27) powders synthesized by sol-gel autocombustion method have been investigated. The samples were sintered in a temperature range of 1000-1200 degrees C for 5 h. The thermal decomposition behavior of as-prepared powder was studied by thermogravimetry (TG), differential thermal analysis (DTA) and infrared spectra (IR). The structural and magnetic properties of powders were investigated by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The grain size calculated by Scherer equation was found in the range of 36-47 nm which is small enough to obtain a suitable signal-to-noise ratio in high density recording media. Hysteresis loop measurements show that the coercivity values lie in the range of 210.61-1602.6 Oe with increasing sintering temperature. Magnetization studies show a significant increase in the values from 15 to 22 emu/g. The dc electrical resistivity is observed to decrease up to a certain value as the temperature increases and then rises at higher temperature. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.