Magnetic characterization of La3+ and Li1+ co-substituted M-type strontium hexaferrite

Effects of stoichiometric La3+–Li1+ co-substitution on magnetic properties of M-type strontium hexaferrites Sr1-xLaxFe12-x/2Lix/2O19 (x = 0, 0.25, 0.4, 0.5, 0.6) have been studied by using crystallographic and magnetic measurements. Samples were prepared thru conventional ceramic technique and their powder X-ray diffraction profiles were checked by the Rietveld method using GSAS package. Field emission scanning electron microscopy images show that lithium addition derives the enhanced degree of grain separation, which significantly affects the coercivity and anisotropy constant as examined by vibrating sample magnetometer measurement. 57Fe Mössbauer spectra of the samples show that Li1+ ions preferentially occupy the 2a sites, which causes the decrease of MS with lithium addition.