【作者】 黄金祥；

【导师】 郝素娥；

【作者基本信息】 哈尔滨工业大学 ， 无机化学， 2006， 硕士

【摘要】 为得到高性能PTC材料,本文采用溶胶-凝胶法制备了Pr、Mn掺杂摩尔分数分别为0.001,0.002,0.003,0.004,0.005和0.006的BaTiO3粉体。所制粉体经TEM分析,粒径在30nm左右,分布均匀。将粉体烧结成瓷后对其进行了Pr扩渗,Mn扩渗,先Pr后Mn扩渗,先Mn后Pr扩渗以及Pr、Mn共同扩渗,并对改性后BaTiO3陶瓷的组成、结构、形貌及电性能的变化进行了研究。对于掺Pr系列,室温电阻率均在105m数量级,比纯BaTiO3陶瓷的1012m有明显降低;掺Pr摩尔分数为0.004的BaTiO3陶瓷经Pr元素气相扩渗后室温电阻率最低,为0.35m,再对其进行Mn元素气相扩渗,出现了明显PTC效应。对于掺Mn系列,室温电阻率均在1013m数量级,比纯BaTiO3陶瓷的室温电阻率要高,但Mn元素的加入对提升陶瓷PTC效应是有利的;Pr、Mn气相扩渗后室温电阻率也明显降低,最低为2.01m。纯BaTiO3陶瓷经Pr、Mn两种元素共同扩渗后,在25℃~300℃范围内,电阻率可由104m数量级降至102m数量级,出现了NTC效应。XRD测试表明,Pr、Mn气相扩渗后BaTiO3陶瓷的钙钛矿结构没有发生明显改变。XPS测试结果表明,Pr、Mn气相扩渗后BaTiO3陶瓷中均存在相应被扩渗元素,且有C元素存在。Ba、Ti和O的结合能比纯BaTiO3陶瓷中的Ba、Ti和O的结合能均增大2eV,而Pr、Mn掺杂BaTiO3陶瓷中的Ba、Ti和O的结合能均比纯BaTiO3陶瓷中的Ba、Ti和O的结合能高11eV左右,证明气相扩渗法能将化学元素引入到陶瓷体系中。SEM测试表明,Pr、Mn气相扩渗后,BaTiO3陶瓷晶粒生长完整,粒度分布均匀,气孔率下降。更多还原

【Abstract】 In order to get high performance PTC material,different kinds of Pr/Mn modified BaTiO3 powders whose doping mole fraction was 0.001, 0.002, 0.003, 0.004, 0.005 and 0.006 separately were prepared by sol-gel method. The prepared powders were analyzed by TEM,the grain sizes were about 30nm and the grains distributed equalitily.Then the powders were sintered for preparing ceramics,the sintered ceramics were penetrated by Pr,Mn,Pr fistly and then Mn,Mn firstly and then Pr,Pr and Mn together.Then constitutes,structures.appearances and electric capability of the modified BaTiO3 ceramics were investigated.For the BaTiO3 ceramics doped by Pr, resisitivity at room temperature are all about 105m,which is much lower than that of BaTiO3 ceramic,which is 1012m;The resisitivity of the BaTiO3 ceramics doped by 0.004 mole Pr and then penetrated by Pr is the lowest ,it is 0.35m;Then the ceramic was penetrated by Mn,and the effect of the positive temperature coefficient of resistivity appeared. For the BaTiO3 ceramics doped by Mn, resisitivity at room temperature are all about 1013m,which is higher than that of BaTiO3.But the doping of Mn can increase the peak value of PTC effect. And the lowest resisitivity is 2.01m after penetration.The BaTiO3 showed the effect of negative temperature coefficient of resistivity after it was penetrated by Pr and Mn together,and the resistivity could decrease from 104 mto 102 m.The results of XRD test showed that ,the perovskite structure of BaTiO3 penetrated by Pr/Mn did not change obviously.The results of XPS test showed that ,the correspond element and the element carbon were found in the BaTiO3 after it was penetrated, and the binding energys of Ba,Ti and O were all increased 2eV than those in the pure BaTiO3 ceramic,but those in the BaTiO3 ceramic doped by Pr or Mn were all increased 11eV. All of these indicated that the method of gas penetration could make the elements into the cramics.The results of SEM test showed that,after pentration of Pr or Mn,the gowth of the BaTiO3’s grain was more integrity , the grains distributed equally and the porosity declined.更多还原