Synthesis of Co_xMg_1−xAl₂O₄ nanospinel pigments by microwave combustion method

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• 作者：R.M. Khattab ; ^{rihamkhattab78@yahoo.com" class="auth_mail" title="E-mail the corresponding author} ; H.E.H. Sadek ; A.A. Gaber
• 关键词：Ceramics ; Microwave ; Pigment ; Chemical analysis and testing ; Optimization techniques
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：43
• 期：1
• 页码：234-243
• 全文大小：4636 K

文摘

The aim of the work is optimizing the calcined temperature for Co_xMg_1−xAl₂O₄ nanospinel pigment formation after microwave treatment. The powders were prepared by the microwave combustion method (MCM), using Magnesium chloride hexahydrate (Mg(Cl)₂·6H₂O), cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O) and Aluminum chloride hexahydrate (Al(Cl)₃·6H₂O), as starting materials and starch as a fuel. The powder precursors were calcined at different temperatures; 400 °C, 550 °C and 800 °C to optimize the nanospinel formation. The properties of products were characterized using differential thermal analysis and thermogravimetric analysis (DTA/TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectra (IR) and transition electron microscope (TEM). Finally, determination of the magnetic properties of nanocrystalline Co_xMg_1−xAl₂O₄ spinel powders was performed by means of Mössbauer spectroscopy, using a vibrating sample magnetometer (VSM). The results revealed that Co_xMg_1−xAl₂O₄ compositions exhibited crystal size below 35 nm except for the powders containing high level of the cobalt content. The particle size was below 100 nm except for the MgAl₂O₄. The diffuse reflectance spectra of the Co_xMg_1−xAl₂O₄ pigments confirmed the presence of tetrahedrally coordinated Co²⁺. Magnetic measurements revealed that the nanocrystalline Co_xMg_1−xAl₂O₄ have ferromagnetic behavior. Therefore, the present experiment succeeds in synthesis of nanospinel blue compositions in short time based on microwave combustion method to be applied in various applications such as in the fields of pigment, ceramic and magnetic applications.