Modification of nanostructured mixed hexaferrite using a polyethylene glycol template

The present Letter deals with the investigation on the synthesis and properties of nanostructured mixed barium hexaferrites of M-type (BaFe₁₂O₁₉) and Y-type (Ba₂Co₂Fe₁₂O₂₂). The nanoparticles of mixed hexaferrite (Ba-M-Y) were obtained using co-precipitation technique with and without addition of polyethylene Glycol (PEG) during synthesis. The precipitate was calcined at 600-C for 6-h and characterised for structural, morphological, electrical and microwave properties. PEG acts as a template for the formation of hexaferrite nanoparticles. Significant reduction in crystallite size and grain size was obtained for Ba-M-Y synthesised in the presence of PEG template. Owing to PEG template the temperature-dependent resistivity showed negative temperature coefficient properties whereas without PEG the Ba-M-Y showed positive temperature coefficient properties. The microwave dielectric constant of Ba-M-Y-PEG (5.5 at 10.4-GHz) was higher than that of Ba-M-Y (4.1 at 10.4-GHz). Owing to PEG the microwave absorption increases to almost 50- from less than 1- in the10-10.7-GHz range.