Magnetic anisotropy and (BH)max studies in microwave sintered Al- substituted strontium hexaferrite.

Al-substituted strontium hexaferrite (SrFe 12-x Al x O 19) has been synthesized by the sol-gel auto-combustion method, followed by microwave sintering at 1100 °C. The Rietveld refinement of XRD patterns reveals the hexagonal crystal symmetry with P6 3 /mmc space group. Lattice contraction has been observed with the increasing Al3+ concentration in SrFe 12-x Al x O 19. The anisotropy field is found to be ∼25 kOe for SrFe 11·5 Al 0·5 O 19. The (BH) max (maximum energy product) of 1.20 MGOe is obtained for x = 0.0 whereas there is a 63.66% enhancement of coercivity for SrFe 11·5 Al 0·5 O 19 at 300 K. However, the highest (BH) max of 1.84 MGOe has been achieved at 60 K for SrFe 11·5 Al 0·5 O 19. The criterion for a permanent magnet is satisfied by analyzing the hardness parameter. All the samples are found to be magnetically hard with (BH) max in the range (1.00–1.20) MGOe at 300 K. • Lattice contraction in SrFe12-xAlxO19 (0≤x≤0.5) • All the synthesized samples are magnetically hard • Enhancement of anisotropy field up to 25 kOe • Uniform magnetic interaction confirmed by ΔH vs M plot • Highest (BH)max of 1.84 MGOe achieved for SrFe11.5Al0.5O19 at 60 K [ABSTRACT FROM AUTHOR]