Electronic structure and multiferroic properties of (Y, Mn)-doped barium hexaferrite compounds

We have systematically studied the crystal and electronic structures and the magnetic and electrical polarization properties of polycrystalline Ba0.95Y0.05Fe12-xMnxO19 (denoted as BaYFe12-xMnxO19.) compounds with x = 0-2. The analyzes of X-ray diffraction patterns and Raman scattering spectra indicated their single phase in the M-type hexaferrite structure. With increasing x, the lattice constant a slightly increased while c decreased, which related to the Jahn-Teller effect. Though an increase of x reduced gradually magnetization in a range of 23-32 emu/g, the coercive force increased from 3.3 kOe for x = 0 to about 4 kOe for x = 0.5-2. The study of the electrical polarization properties proved the dependence of the shape of electric hysteresis loops on x and applied electric field. The samples with x = 0 and 0.5 exhibit a weak ferroelectricity with the maximum polarization of similar to 0.11 mu C/cm(2) for x = 0, and of similar to 0.06 mu C/cm(2) for x = 0.5. Meanwhile, the other samples showed nearly circular hysteresis loops, which are characteristic of conductive materials. Detailed investigations indicated an increase in leakage current when x increased. All of such phenomena are tightly related to the chemical shift of Mn2+-> Mn3+ and the replacement of Mn-2+,Mn-3+ for Fe3+ in BaYFe12-xMnxO19. These oxidation states and the chemical shift of Mn have been confirmed upon analyzing X-ray absorption spectra. (C) 2021 Elsevier B.V. All rights reserved.