Magnetic properties of polycrystalline Y-type hexaferrite Ba2-xSrxNi2(Fe1-yAly)12O22 using Mossbauer spectroscopy

Synthesis of the polycrystalline Ba2-xSrxNi2(Fe1-yAly)(12)O-22 (x = 0.0, 1.5, y = 0.00, 0.01, and 0.03) was accomplished by employing the polymerizable complex method. The samples were investigated for the crystallographic and magnetic properties by x-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Mossbauer spectrometer. Based on the results of the refined XRD patterns, all samples were confirmed to have a rhombohedral structure with space group R-3m. Moreover, six distinguished sublattices were identified, which were four octahedral sites (18h(VI), 3b(VI), 6c(VI), and 3a(VI)) and two tetrahedral sites (6c(IV)(star), 6c(IV)). The lattice constant of a(0) and c(0) decrease via Sr, Al substitution because the ionic radius of Sr2+ (1.12 angstrom) is smaller than that of Ba2+ (1.34 angstrom), and the ionic radius of Al3+ (0.535 angstrom) is smaller than that of Fe3+ (0.645 angstrom). The zero-field-cooled (ZFC) measurement was applied at 100 Oe between 4.2 and 295 K and it revealed the spin transition temperature (T-S). Substitution of Sr ions increased T-S. Al ions were further substituted after the substitution of Sr ions, and T-S increased above room temperature. The Mossbauer spectra fit six distinguish sublattices: 18h(VI), 3b(VI), 6c(IV), 6c(IV)(star), 6c(VI), and 3aVI. The isomer shift of all samples indicated that the charge state of Fe ions is Fe3+. The Mossbauer spectra obtained with respect to temperature change confirmed the changes in the magnetic hyperfine field curves at T-s. (c) 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).