x Effects of divalent ions substitution on the microstructure, magnetic and electromagnetic parameters of Co2W hexagonal ferrites synthesized by sol-gel method

Divalent (Me) ions substituted W-type hexagonal ferrites with chemical formula Ba0.5Sr0.5Co2 xMexFe16-O-27 (x = 0, 0.5 and Me = Mn, Mg, Zn, and Ni) were prepared by sol-gel autocombustion method at 1300 degrees C for 5 h. Thermal and IR spectral studies were carried out by means of differential thermal/thermogravimetric analysis and Fourier transform infrared spectroscopy respectively. The microstructure was investigated by using the powder X-ray diffractometer and the field emission gun scanning electron microscope. The results showed that divalent ions substituted W-type hexagonal ferrites were single phase and appeared as hexagonal platelet-like shape which is better shape for microwave absorption. M-H loops of a selected sample were measured up to maximum applied field of 9T in a temperature range of 4.2-400 K. The values of saturation magnetization were calculated by the law of approach to saturation. The room temperature value of coercivity is found to be a few oersteds which is favorable for EM materials. Based on the results of electromagnetic parameters, reflection losses were calculated which are found to depend on the thickness of the absorber. (C) 2013 Elsevier B.V. All rights reserved.