A systematic study of physical properties of La substituted Sr3Co2Fe24O41 Z-hexaferrites

Abstract

The impact of La substitution has been explored systematically in the present work, it covers a rough scan of the range of solubility of Lanthanum in the Sr3Co2Fe24O41 (SCFO) structure. The La substituted Z-type hexaferrites Sr3-xLaxCo2Fe24O41, with x = 0.00, 0.15, 0.30, and 0.45, have been prepared via solid-state reaction route and named as SCFO, SLCFO5, SLCFO10 and SLCFO15 respectively. The structure and particle morphology of the samples have been investigated via variety of structural characterization methods like X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). A substantial change in structural properties beyond x ≥ 0.45 suggests that their exists a limit of Lanthanum solubility in the Sr3-xLaxCo2Fe24O41 which is x = 0.45. The dielectric properties (ε′ & ε′′) of SCFO, SLCFO5, SLCFO10 and SLCFO15 were examined by varying temperature from 313 to 613 K in the frequency range of 500 Hz to 10 MHz. The dielectric responses of all the samples are frequency-dependent and thermally stimulated, with relaxation-type dielectric behavior. From M-H loops, it has been observed that with increasing La substitution, the saturation magnetization value reduces from 63.85 to 59.17 emu/g, whereas coercivity increases from 109.74 to 450.51 oersted, indicating an increase in magnetic hardness. The saturation magnetization (Ms) and Magneto crystalline anisotropy constant (K1) were calculated by fitting the experimental data. A weak signature of magneto-electric coupling is observed by employing an indirect method in the SCFO sample.