【作者】 侯军刚；

【导师】 马卫兵；

【作者基本信息】 天津大学 ， 材料学， 2007， 硕士

【摘要】 MnZn铁氧体作为软磁性材料被广泛用于通讯、汽车、医疗、工业、军事和宇航等领域。随着现代设备的高性能、高密度和高可靠性的要求,LTCC(Low Temperature Co-fired Ceramics)封装技术成为了现代研究的热点。由于内电极的共烧要求,LTCC的烧结温度要控制在900℃以下。作为其中的主要元件之一,电感磁性材料的烧结温度也要控制在900℃以内。本文通过液相法合成超细纳米粉体以及添加助烧剂的办法实现低温烧结。首先,以分析纯的硝酸铁、硝酸锰、硝酸锌、柠檬酸、氨水、硝酸以及去离子水为主原料,分析纯的硝酸铜、硝酸铋为添加剂原料,利用干凝胶自蔓延燃烧工艺合成纳米级MnZn铁氧体粉体,用X衍射(XRD)仪和透射电子显微镜(TEM)分析了粉体的晶体结构、粉体粒径及颗粒分布程度。综合分析了原料、络合剂、pH值、硝酸盐浓度以及热处理对纳米铁氧体粉体的生成过程及粉体结构的影响,试图寻找最佳的粉体制备工艺条件。其次,在MnZn铁氧体原始配方中加入不同的少量添加剂Cu(NO3)2·3H2O和Bi(NO3)3·5H2O,所制得的干凝胶,自燃烧后获得的粉末加入一定量的酒精,反复冲洗三次,然后球磨、烘干、造粒并干压成圆片状坯体。将坯体在850℃、875℃、900℃、930℃、950℃的温度下烧结,低温合成了一系列的Mn0.5Zn0.5Fe2O4+xBi2O3/ CuO/ (CuO-Bi2O3)铁氧体(x=0~8wt%)。利用扫描电子显微镜(SEM)、振动样品磁强计(VSM)研究了烧结MnZn铁氧体的成相、致密化和磁性能。实验结果分析,纳米级粉体制备的纯MnZn铁氧体,烧结温度为930℃;CuO引入,烧结温度降到900℃,MnZn铁氧体的磁性能有一定的提高。Bi2O3引入,烧结温度虽降到850℃,但损失了磁性能。CuO-Bi2O3引入,其磁性能大幅度提高:磁导率188,比饱和磁强度60.09emu/g。综上所述在Mn0.5Zn0.5Fe2O4的基础上掺杂CuO-Bi2O3,可得到低温烧结、优良磁性能的MnZn铁氧体。更多还原

【Abstract】 MnZn ferrite materials are extensively applied in telecommunications, cars, industry, military affairs and space navigation etc. With the trend of modern electronic applications towards optimum properties, high density and high reliability, LTCC technology is paid more attention to being an hotspot. Due to co-fired request of inside electrode, it is required to control sintering temperarture of LTCC technology less than 900℃. For one of important component, sintering temperarture of LTCC technology will be also controlled less than 900℃. Liquid phase method prepared nanopowders and added additives is used to lower sintering temperarture in this paper.Firstly, Soft magnetic MnZn ferrite nanoparticles were prepared by a novel sol-gel auto-combustion method using Mn(NO3)2,Fe(NO3)3·9H2O and Zn(NO3)2·6H2O as a starting materials dissolved in water and citric acid. The powder was charactered by X-ray diffraction analysis and transmission electron Microscope (TEM) method. The effects of process and powders structure were further studied, considering and analyzing raw materials, complexing agent, pH value, concentration, heat treatment.Secondly, Soft magnetic MnZn ferrite powders were washed repeatedly by alcohol, then groud, dried, made grains and pressed into wafer. At 850~950℃, Mn0.5Zn0.5Fe2O4+xBi2O3/CuO/(CuO·Bi2O3) (where x=0~8wt%) ferrites were prepared under low temperatures. The effects of on phase formation, densification process, and magnetic properties were further studied by scanning electron microscope (SEM) and vibrating samples magnetometer (VSM).The experimental results show that sintering temperature of pure MnZn-ferrite is only 930℃. An appropriate amount of Bi2O3 can lower the sintering temperature obviously to 850°C but sacrifice the magnetic property. An appropriate amount of CuO and CuO-Bi2O3 can also lower the sintering temperature below 900°C and improve the magnetic property which high values of the permeability and the saturation magnetization are 188 and 60.09 emu.g-1 respectively. Thus CuO-Bi2O3 is subsequently evaluated for its contribution to lower the sintering temperature and improve the magnetic property of MnZn-ferrites.更多还原