Effect of heat-treatment on the magnetic and optical properties of Sr0.7Al0.3Fe11.4Mn0.6O19

Sr0.7Al0.3Fe11.4Mn0.6O19 was synthesized by sol-gel technique and sintered at varying temperatures 750 degrees C, 850 degrees C, 950 degrees C and 1050 degrees C for 5 h. We investigate the role of heat-treatment on the structural, magnetic and optical properties of Al-Mn doped strontium hexaferrite. XRD analysis indicates the formation of M-type hexaferrites with some traces of alpha-Fe2O3. The presence of two prominent peaks between 400 cm(-1) and 600 cm(-1) in the spectra of FTIR gives the possibility of the emergence of M-type hexagonal ferrites. FESEM micrograph shows that the grains of the prepared sample possess Plate-like hexagonal structure. EDX spectra confirmed the stoichiometry of the prepared sample. Recrystallization of the synthesized sample and formation temperature of 650 degrees C is observed in TGA analysis. Variation of the sintering temperature results in decrease of the band gap. Magnetic parameters were calculated from the M-H loop obtained from vibrating sample magnetometer (VSM). High value of coercivity (6750 Oe) is observed at 850 degrees C. Remanent and saturation magnetization decreases with increase heat-treatment temperature. The synthesized sample may be useful in perpendicular recording medium (PRM) and high frequency application.