Temperature dependent structural and magnetic behavior of Y-type hexagonal ferrites synthesized by sol-gel autocombustion

A Y-type hexaferrite (Sr2Ni2Fe12O22) sample was synthesized using the sol-gel autocombustion and heat treated at different temperatures (800-1200 degrees C). Different experimental techniques such as differential thermal and thermo-gravimetric analyses, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry were used to investigate the sample. The X-ray diffraction analysis shows that Y-type hexaferrite begins to appear at 1000 degrees C and the formation of pure Y-type hexaferrite phase gets completed at 1200 degrees C. IR spectrum for sample heat treated at 1200 degrees C further confirms that single phase sample of Y-type hexagonal ferrite can be prepared at this temperature. The highest values of coercivity and saturation magnetization were achieved at a temperature of 1000 degrees C due to the presence of M-type hexaferrite. Moreover single phase Y-type hexaferrite sample has a coercivity of a few hundred oersteds which is suitable for security, switching, sensing and high frequency applications. (C) 2015 Elsevier B.V. All rights reserved.