Study Of TiO₂-doped LaMnO₃ System NTC Material

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.