Characterization of Sr-substituted W-type hexagonal ferrites synthesized by sol-gel autocombustion method

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• 作者：Mukhtar Ahmad^a ; ^{ahmadmr25@yahoo.com} ; R. Grö ; ssinger^b ; M. Kriegisch^b ; F. Kubel^c ; M.U. Rana^a ; ^{mazharrana@bzu.edu.pk}
• 关键词：W-type hexaferrites ; Sr-substitution ; Sol&ndash ; gel ; Microstructure ; Magnetic properties ; Microwave absorption
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：2013
• 出版时间：April, 2013
• 年：2013
• 卷：332
• 期：Complete
• 页码：137-145
• 全文大小：1145 K

文摘

The magnetic and microwave characterization of single phase hexaferrites of entirely new composition Ba_1-xSr_xCo₂AlFe₁₅O₂₇ (x=0.2-1.0) for application in a microwave absorber, have been reported. The samples synthesized by sol-gel method were investigated by differential thermal analyzer, Fourier transform infrared spectroscope, X-ray diffractometer, field emission gun scanning electron microscope, vibrating sample magnetometer and vector network analyzer. Platelet grains exhibit well defined hexagonal shape which is a better shape for microwave absorption. M-H loops for a selected sample were measured for a temperature range of 4.2-400 K. Moreover M-H loops for all Sr-substituted samples were also measured at room temperature up to a maximum applied field of 9 T. Saturation magnetization values were calculated by the law of approach to saturation. The room temperature coercivity for all the samples is found to be a few hundred oersteds which is necessary for electromagnetic materials and makes these ferrites ideal for microwave devices, security, switching and sensing applications. The complex permittivity, permeability and reflection losses of a selected ferrite-epoxy composite were also investigated over a frequency range of 0.5-13 GHz.