研究了溶胶-凝胶自燃烧法制备CoY_(0.1)Fe_(1.9)O_4的成胶热力学条件和自燃烧的过程,从理论和实验讨论了pH值和柠檬酸量对产物的影响.利用热重/差热综合分析仪及X射线衍射仪对干凝胶的热反应特性和晶体结构进行了测试和分析.利用振动样品磁强计研究了不同柠檬酸量产物的矫顽力.实验结果表明,由Fe、Co和Y元素与水的二元体系的平衡电势(E)-pH图确定的溶液成胶pH值与实验结果相符合;通过计算氧化剂正价态和燃料的负价态的平衡系数,获得混合硝酸盐与柠檬酸的理论比值为2.3.取过量的柠檬酸量,能够合成尖晶石结构的CoY_(0.1)Fe_(1.9)O_4纳米粉末.随着柠檬酸量的继续增加,产物中有Fe_2O_3的出现,且矫顽力减小.
The process of self-combustion and thermodynamic condition of gel formation of CoY_(0.1)Fe_(1.9)O_4 ferrite powder were studied for a sol-gel self combustion method,discussed the influences of pH value of the precursor solution and concentration of the chelation citric acid to samples.Thermal reaction process and the structure of amorphous gelatin were studied by thermogravimetric-differential thermal analysis(TG/DTA)and X-ray diffraction(XRD respectively).The component and magnetic properties of powders were investigated by XRD and vibrating sample magne-tometer(VSM).The experiments showed that the conditions of pH value of the mixed precursor solutions for gel formation by corrosion figure(E-pH figure)of Fe,Co and Y with water systems have same result with experiment.The content ratio 2.3 of citric acid and mixed nitrate is obtained through calculating the balance coefficient of positive valence of oxidant and negative valence of fuel.The CoY_(0.1)Fe_(1.9)O_4 ferrite powder can be prepared by putting excessive citric acid into the precursor solution.With the gradual increasing citric acid content,the Fe_2O_3 came out from powder and the coereivity decreases.
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