材料期刊网

采用以硫酸锰、硫酸锌、硫酸亚铁以及柠檬酸为原料的溶胶-凝胶方法制备热敏锰锌铁氧体.在900℃煅烧,得到锰锌铁氧体的粉体.将粉体压成环形样品,在平衡气氛下,1350℃烧结.采用扫描电镜(SEM)分析锰锌铁氧体烧结体的显微结构;用HP4192,测量从室温到150℃的烧结体的磁导率.结果表明在800℃热处理,得到尖晶石结构的锰锌铁氧体粉体.在平衡气氛下,1300℃烧结2 h,得到尖晶石结构的锰锌铁氧体烧结体.扫描电镜(SEM)图谱显示烧结体显微结构致密,晶粒平均尺寸大约在5-10μm:锰锌热敏铁氧体的磁导率μi在居里温度附近发生突变,说明锰锌热敏铁氧体的磁性由铁磁相转变为顺磁相:在铁离子含量不变的条件下,随着锌离子含量(Zn2+)的增加,锰离子含量(Mn2+)的减少,锰锌热敏铁氧体的居里温度降低;锰锌热敏铁氧体的磁导率μi,随着锌离子含量(Zn2+)的增加而降低.

Thermal sensitive manganese zinc ferrites with various stoichiometry were prepared from sol-gel-derived powders.Manganese sulfate,zinc sulfate,ferrous sulfate and the citric acid were selected as raw materials in the sol-gel process.Manganese zinc ferrites powders were obtained after calcined at 900℃.Under the balanced atmosphere,the ring-like samples were sintered at 1350℃.The microstructure of manganese zinc ferrites was analyzed by X-ray diffraction(XRD)and scanning electron microscopy(SEM);with HP4192 LCR meter,the magnetic properties of the samples were obtained from room temperature to 150℃.The result indicated that manganese zinc ferrites powder was the spinel structure after calcined at 800℃in air for 2 h.Under the balanced atmosphere,after sintered at 1350℃for 2 h,the spinel structure remained.The SEM showed the microstructure of the samples was compact and the grain size was approximately 5 μm.The magnetic permeability of thermal sensitive manganese zinc ferrites had a sudden change near the Curie temperature,which can be explained by the ferromagnetic to paramagnetic phase transition.It Was found that Tc reduced linearly with increasing Zn2+extent when the content of Fe2O3 was fixed.