Sanjay R. Gawali, Kishor G. Rewatkar and Vivek M. Nanoti
M-type calcium ferrites with substitution of Fe3+ by Al3+ were prepared by sol-gel auto-combustion technique by blending nitrates as oxidants accompanied with fuels like urea as reducing agents. The powders were characterized using XRD and TEM. The XRD analysis indicated that the formation of single phase substituted M-type calcium hexaferrites. The average particle size of the powders were close to 94 nm. The electrical conductivity of the synthesized samples was carried out by a four – probe method in the same temperature range i.e. 300 K – 873 K. The value of ln(s) of the samples decreases almost linearly with increasing reciprocal temperature upto transition temperature. The DC electrical resistivity of the samples at room temperature was also increases with increase in the concentration of Al3+ in the hexaferrite samples. The enhanced resistivity of the aluminium doped calcium hexaferrite is potential applicant in microwave devices. The drift mobility of samples was calculated from the electrical resistivity data.
