Magnetic Characterization of Ca-Hexaferrites Using Hysteresis Technique

Abstract

In the present investigation the samples with chemical composition Ca_1-x-y(CoTi)_0.5Mn_xZn_yFe₁₁O₁₉ with (x = y = 0-0.5) were synthesized using perfect stoichiometric proportions of reacting oxides by standard ceramic technique. Hexagonal magnetoplumbite (M) structure having unit cell dimensions 'a' and 'c' which varies in the range between 5-6 Å and 21-23 Å with space group P6₃/mmc (No. 194). The coercivity, retentivity, saturation magnetization and magnetic moment increases successively with increase in Mn-Zn concentration by changing magnetic field at 300 K. The room temperature resistivity increases in the range of 10⁶ W cm. The grain size of the studied compounds varies in the range 0.29-0.79 mm (i.e., 290-790 nm). The superexchange interaction, Me-O-Me is responsible for magnetic behavoiur and found to increase with the increase of the Mn-Zn concentration in Ca-M compounds. It is found that there is a variation in hysteresis loops with change in magnetic field. The neutron diffraction and NMR studies also reveals that Co³⁺ ions are mainly distributed within 4f_iv and 12 k sites of the studied compound.