【作者】 郝艳霞；

【导师】 马卫兵；

【作者基本信息】 天津大学 ， 材料学， 2005， 硕士

【摘要】 本文介绍了制备NTCR半导体材料的新方法,即着重于和国际水平差距很大的感温元件,结合NTC热敏电阻器灵敏度高、阻值易于调控、但线性差的实际,寻找能够产生线性NTC效应的合适的掺杂材料,同时给出规模化的实验流程。本实验尝试提高LaMnO₃电阻率使其应用于半导体方面,通过控制氧八面体中不同价态的可变价离子的含量来控制电导率。当需要提高材料电阻率时,根据稀释原理,可引入同价的或高价的离子,这相当于降低了单位体积内的可变价的异价离子的含量,从而提高了材料的电阻率。利用掺杂的方法结合固相反应法,控制掺杂量来控制施主或受主的浓度从而控制半导体的电性能。故首选选择了SrCO₃、SnO₂和TiO₂进行掺杂,经过对实验结果的分析找出适合的掺杂材料为TiO₂。在实验初期先对LaMnO₃进行不同的TiO₂量的掺杂,通过对实验结果的分析,同时利用XRD、SEM等手段对材料的物相进行了分析并对材料的微观形貌进行了观察和研究,在此基础上选出几个具有低阻高B的配方(LaTi_xMn_1-xO₃,x=0.3、0.4、0.5和0.6)进行A位或B位的微掺杂氧化物或碳化物:CuO、BaCO₃、Nb₂O₅、Cr₂O₃、SrCO₃和Y₂O₃,掺杂量小于0.2%mol,并相应的采取不同的合成温度、烧结气氛和保温时间,以获得高线性的、稳定性好的、B值和电阻率可调的NTC热敏陶瓷材料。通过进一步的实验与分析找出了符合实验目的的微掺杂的氧化物或碳酸盐。更多还原

【Abstract】 In this paper, a new method of making NTCR semiconductor material was introduced, which could cut the gap of sensitive and temperature components between the international level, and was able to find the appropriate dopant material with NTC effect, combining the fact that thermal resistors have high sensitivity, controlling resistance easy and bad linearity. Then the experiment process was laid out in order.In this experiment, we tried to increase resistivity of LaMnO₃. Conductance values could be controlled through controlling the number of alterable ions of different valences in oxygen octahedron. According to dilution principle, the same or high valence ions could be replaced, which was equal to decreasing the number of alterable and diverse valent ions, consequently resistivity of materials increases. The semiconductor’s electric property was controlled through controlling the concentration of donor or acceptor by controlling dopant concentration. So SrCO₃, SnO₂ and TiO₂ were choiced to doped in LaMnO₃, analyzing the results, Ti’s droping was the suitful dopant material.At the beginning of experiment, TiO₂ was droped in LaMnO₃ with different concentration. The microstructure model and the potential barrier model were proposed in this article through analyzing the results and detecting the microstructure by means of XRD, SEM, then some good sample(LaTi_xMn_1-xO₃,x=0.3, 0.4, 0.5 and 0.6)were selected to micro-doped in A side or B side with oxide or carbide: CuO, BaCO₃, Nb₂O₅, Cr₂O₃ , SrCO₃ and Y₂O₃, which doped less than 0.2%mol. After future experiment and analysis, the ideal dopant oxide or carbide was found.更多还原