Structural, Dielectric, and Magneto‐Optical Properties of Al‐Cr Substituted M‐Type Barium Hexaferrite

Abstract

M‐type barium hexaferrite, BaFe 12‐2 x Al x Cr x O 19 ( x = 0.0, 0.2, 0.4), is prepared using sol–gel auto‐combustion method and calcined at 1000 °C for 7 h. The effects of Al‐Cr substitution on the properties of the barium hexaferrite are investigated through XRD, FTIR, FESEM, UV‐vis‐NIR, VSM, and impedance analyzer. XRD analysis reveals the formation of hexaferrites with single phase and no impurity phase is detected. FTIR spectra show bands at 437 and 590 cm −1 which indicate the possible of hexaferrites. The micrographs of FESEM shows agglomerated grains with hexagonal plate‐like shape while the EDX spectra confirm the composition of the synthesized samples. Dielectric constant decreases abruptly at lower frequencies and an increment in dielectric constant at much higher frequency region is observed. Grain boundaries dominate the AC conductivity at lower frequencies while the grains could be responsible for the observed dispersion at higher frequencies. The values of coercivity for all the samples are found to be greater than 1200 Oe; this makes the prepared samples useful for high‐density perpendicular magnetic recording media.