Magnetic Properties of Nanocrystalline Ca2-Y Hexaferrite on Al-Substitution

Calcium hexaferrites doped with Al3+ ion, Ca2Zn2Fe12-xAlxO22 (x=0, 0.7 and 1.0) were prepared microwave induced sol-gel combustion technique. The structure properties of the calcined samples were studied using powder X-ray diffraction (XRD). All the XRD patterns showed the single phase of the Y-type calcium hexaferrites without other intermediate phase. The lattice parameters of the synthesized sample were found to increase with increase substitution of Al3+ ion for Fe3+ ion, which is attributed to the ionic size differences of cations involved. The morphological properties of the synthesized samples were measured by using SEM. The SEM study have shown that the sample exhibit relatively well defined, hexagonal like grains with average size of less than 80 nm. X-ray density was found to decrease with the substitution. The bulk density of the sample was increased whereas the porosity was decreased with the increase in the substitution. The dc electrical conductivity measurements have been carried out over the temperature range 300 K – 800 K by using impedance analyzer. The electrical conductivity of the sample was explained on the basis of hopping mechanism. The resistivity of the sample was found to be enchacing with the substitution of Al3+ ion for Fe3+ ion which has potential applications in microwave devices. The magnetic properties of the samole at room temperature were studied by VSM. The coercivity of the sample was found to be enchanced which enable its use as a permanent magnet