Influence of Cd substitution on structural, electrical and magnetic properties of M-type barium hexaferrites co-precipitated nanomaterials

摘要

Nanocrystalline M-type hexagonal ferrites with the nominal chemical composition Ba_(0.5)Co_(0.5-x)Cd_xFe_(12)-O_(19) (where x = 0-0.5) have been synthesized by the co-precipitation method and sintered at high annealing temperature (1250 °C) to study their structural, electrical and magnetic properties. The aim of the present work is to increase the DC electrical resistivity and coercivity of these M-type hexaferrites nanomaterials by the substitution of cadmium (Cd~(2+)) ions at CO~(2+) site. The analysis of X-ray diffraction (XRD) patterns indicates single M-type hexaferrite phase. The parameters such as lattice constants (a and c), cell volume (V), X-xay density (D_x), bulk density (Db), crystallite size (D) and percentage porosity (%P) were calculated from XRD data. The crystallite size is found in the range of 26-47 nm and this size is small enough to obtain a suitable signal-to-noise ratio for application in the magnetic recording media. The room temperature DC electrical resistivity increases from 2.31 × 10~9 Ω cm to 6.42 × 10~9 Ω cm with the increased Cd contents. The magnetic properties such as saturation magnetization (M_s), coercivity (H_c), remanence (M_r) and squareness ratio (M_r/M_s) were calculated from hysteresis loops. The coercivity increases from 155 Oe to 1852 Oe while the saturation magnetization decreases from 33.5 to 9.2 emu g~(-1) as the concentration of Cd increases. The electrical and magnetic properties such as DC electrical resistivity, coercivity and remanence suggested the synthesized materials suitable candidate for high frequency applications and recording media.