Influence of La–Mn substitutions on magnetic properties of <italic>M</italic>-type strontium hexaferrites.

M-type strontium hexaferrites of Sr_{1−<italic>x</italic>}La_{<italic>x</italic>}Fe_{12−<italic>x</italic>}Mn_{<italic>x</italic>}O₁₉ (0.0≤<italic>x</italic>≤0.4) were synthesized by the chemical coprecipitation method. X-ray diffraction (XRD) studies indicate that the samples are single-phase with the space group of <italic>P6</italic>_{<italic>3</italic>}<italic>/mmc</italic>. The results of field-emission scanning electronic microscopy (FE-SEM) show that the grains are regular hexagonal platelets with sizes from 0.7 to 1.4 μm. It is observed that the value of <italic>H</italic>_{<italic>c</italic>} increases at low substitution (<italic>x</italic> ≤ 0.1), reaches a maximum at <italic>x</italic> = 0.1 and then decreases at <italic>x</italic> ≥ 0.1, while the value of <italic>M</italic>_{<italic>s</italic>} decreases monotonously with increasing <italic>x</italic>. The variations of magnetic properties can be tentatively attributed to the effects of La–Mn substitutions. The results above indicate that our samples might be promising candidates for permanent magnets in the future. [ABSTRACT FROM AUTHOR]