Mossbauer spectroscopy study of Y-type Hexaferrite (Ba2Co2Fe12O22) prepared by the co-precipitation method

In this work we report the results of structural and Mossbauer spectroscopy studies for Ba2Co2Fe12O22 samples prepared by coprecipitation following two different synthesis routes: route A (pH = 10, NaOH + Na2CO3 added dropwise), and route B (pH = 14, NaOH + Na2CO3 added one shot). The resulting powders were sintered for 4 h at different temperatures (700 degrees C to 1100 degrees C in steps of 100 degrees C). The sintered powders were characterized by x-ray diffraction (XRD) and room temperature Mossbauer spectroscopy. XRD and Mossbauer results of the sample prepared by route A and sintered at 700 degrees C revealed formation of spinel phases (CoFe2O4 and/or Fe3O4), BaCO3 and BaM-type phase. The Co2Y phase developed in the samples sintered at 800 degrees C and 900 degrees C with spinel species as impurities, and single (pure) Co2Y phase was obtained at higher temperatures. On contrast, XRD patterns and the Mossbauer spectra for the samples prepared by route B showed different results, where the sample sintered at 700 degrees C consisted of only spinel phases. The Co2Y phase developed at higher temperatures, coexisting with significant amounts of other phases.