Improved magnetic properties of Cr < sup > 3+ < /sup > doped SrFe < inf > 12 < /inf > O < inf > 19 < /inf > synthesized via microwave hydrothermal route

Abstract

Cr doped Sr-hexaferrites (SrCrxFe12-xO19) were prepared using microwave-hydrothermal method and sintered at 950 °C/90 min using single mode microwave furnace. With increasing Cr3+ content, the lattice parameters changed anisotropically, where 'a' increases and 'c' decreases. The average grain sizes of sintered hexaferrite are in the range of 280-660 nm. XPS spectra shows that for higher Cr3+ content i.e., x > 0.3, both Fe2+ and Fe3+ ions are present in the crystal structure. With Cr3+ doping saturation magnetization systematically decreased and coercivity increased. Magnetic hyperfine analysis using Mössbauer technique indicates that Cr3+ ions preferentially occupy 2a, 12k, and 4f1 sites.