Investigation of Magnetic Properties of Sr-Doped Ba 3– x Sr x Co 2 Fe 24 O 41 Z-type Hexaferrite by Mössbauer Spectroscopy

摘要: The polycrystalline Ba3– x Sr Co2Fe24O41 ( $x = 0.0, 0.5, 1.0$ , and 1.5) samples were synthesized by the solid-state reaction method. crystalline structure of was found to be a hexagonal with space group $P6_{3}/mmc$ . lattice constants $a_{0}$ $c_{0}$ $V_{u}$ decrease increasing concentration. From field-dependent hysteresis curves under 10 kOe at 295 K, values $M_{s}$ increase while $H_{c}$ decrease. zero-field-cooled magnetization 100 Oe between 4.2 300 K show spin transition, value $T_{s}$ decreases from 230 for $x=0.0$ 135 1.5$ concentration due reduction planar anisotropy difference in ionic radius Ba2+ Sr2+ ions. isomer shift $\delta $ ) obtained Mossbauer spectra, charge states all are determined Fe3+ high state. With concentration, hyperfine field $\langle H_{\mathrm {hf}}\rangle suggests change interaction Fe ions because larger ion than that ion, leading decreasing