Mössbauer and X-ray diffraction study of Co2+-Si4+ substituted M-type barium hexaferrite BaFe12−2Ñ Ð¡Ð¾Ñ SiÑ O19±γ

► In the range х=0-0.3, homogeneous solid solutions BaFe12−2xCoxSixO19±γ are formed. ► Only Fe3+ions in the high-spin state present in the homogeneous region. ► Со2+, Sі4+ ions prefer to occupy crystallographic positions 12k, 4f1 respectively. ► Substitution 2Fe3+→Со2++Sі4+ decreases particle size and coercivity.