2015/04/09 by Vivek Dixit, Dixit, Vivek, Chandani N. Nandadasa +17
Energy · Materials Science · Physics and Astronomy · #Chemical and Physical Properties of Materials #FOS: Physical sciences #Iron oxide chemistry and applications #Magnetic Properties and Synthesis of Ferrites #Materials Science (cond-mat.mtrl-sci) #Metallurgical and Alloy Processes #Multiferroics and related materials #Transition Metal Oxide Nanomaterials #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.1504.02320
8 pages, 5 figures. arXiv admin note: text overlap with arXiv:1209.5143
openalex publication_date 2015/04/09 · arxiv created 2015/04/27 · arxiv updated 2015/04/28 · openalex created_date 2022/09/25 · openalex updated_date 2026/07/28
We use first-principles total-energy calculations based on density functional theory to study the site occupancy and magnetic properties of Al-substituted M-type strontium hexaferrite SrFe12-xAlxO19 with x=0.5 and x=1.0. We find that the non-magnetic Al3+ ions preferentially replace Fe3+ ions at two of the majority spin sites, 2a and 12k, eliminating their positive contribution to the total magnetization causing the saturation magnetization Ms to be reduced as Al concentration x is increased. Our formation probability analysis further provides the explanation for increased magnetic anisotropy field when the fraction of Al is increased. Although Al3+ ions preferentially occupy the 2a sites at a low temperature, the occupation probability of the 12k site increases with the rise of the temperature. At a typical annealing temperature (> 700 ∘\rm C) Al3+ ions are much more likely to occupy the 12k site than the 2a site. Although this causes the magnetocrystalline anisotropy K1 to be reduced slightly, the reduction in Ms is much more significant. Their combined effect causes the anisotropy field Ha to increase as the fraction of Al is increased, consistent with recent experimental measurements.