Structural, Electrical and Magnetic Properties of La/Al Substituted Nano Calcium Hexaferrites prepared by Sol?Gel Auto-Combustion Method

The Samples of Calcium Nano Hexaferrites CaLa1Fe11O19, CaLa1Al1Fe10O19 and CaAl1Fe11O19 were prepared by Sol-gel auto combustion technique using urea as a fuel. The powders were characterized with X-ray diffraction analysis, revealed the formation of mono phase M type hexagonal ferrite with space group P63/mmc (no194). The SEM and TEM were studied, which confirmed that the sample exhibit relatively well defined hexagonal grains with average particle size in the range 43 nm to 31nm. The values of the lattice parameters supports this confirmation. DC conductivity of bulk samples have been investigated as a function of reciprocal temperature. The measurements were carried out at constant frequency (100Hz). The Activation energies were calculated at both ferrimagnetic and paramagnetic regions. The enhanced resistivity of aluminum doped calcium hexaferrite is a prospective application in microwave devices. The magnetic measurements were carried by using Vibration Sample Magnetometer (VSM). Results of VSM studies shown that, the Al doped sample shows rise in saturation magnetization, significant increase in the coercive field and magnetic remenance. Increase in coercivity and retentivity illustrate that they are hard ferrite materials. Thus the magnetic characters of the Al doped samples are superior than that of La and La-Al doped calcium hexaferrites. It is known that the nano-hexaferrites with such special magnetic properties are highly useful in Data storage applications.