Electrical transport mechanism of aluminum substituted barium hexaferrite magnetic semiconductor

The polycrystalline M-type barium hexaferrite (BaFe 12− x Al x O 19 ) with x = 0.0, 1.0, 2.0, and 3.0 have been prepared by the sol–gel Method. The crystal structure of all the samples is found to be in hexagonal symmetry with P6 3 /mmc space group. The impedance was studied over a range of frequencies (1 Hz–1 MHz) for all the compositions. Direct current (DC) electrical resistivity measurements of all the samples were carried out in the temperature range of 303–775 K. All the samples exhibit the semiconducting behavior. The resistivity increases with the increase in Al 3+ substitution. The impedance along with DC resistivity results established the electron hopping conduction mechanism in the Al 3+ substituted barium hexaferrites. The electrical conductivity has been well explained by the Mott variable-range hopping mechanism of localized polarons. The dielectric dipoles are frozen at low temperature and activated at high temperature as observed two transition temperatures in temperature versus impedance plot. A correlation between ac impedance and DC resistivity has been established in the M-type hexaferrite magnetic semiconductor.