Effect of three-step calcination on structural, magnetic and microwave properties of BaFe11.5Ti0.5O19 hexaferrite

BaFe12O19 and BaFe11.5Ti0.5O19 were prepared by three-step calcination method. Phase analysis and microstructural study were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Site occupancy of Ti4+ ions with calcination step were investigated by Fourier-transform infrared (FTIR) and Raman spectroscopy. The magnetic and microwave properties (K-u-band) were measured by vibration sample magnetometer and vector network analyzer. XRD patterns confirmed the hexaferrite phase formation in all samples. FTIR showed the presence of Ti4+ ions at spin down octahedral and tetrahedral sites. The peak shift in FTIR and Raman spectra suggested that ion occupancy increases with calcination step. A drastic decrease in the coercivity was observed with substitution. Low dielectric and magnetic losses in were observed in Ti- substituted samples. SEM revealed that Ti- substitution promotes hexagonal grain with decreased size. Overall microwave absorbance was greatly improved by three step calcination method.