题名 | Co-Mn-Ni-Fe-O NTC热敏电阻材料的制备与性能研究 |
作者 | 张东炎 |
答辩日期 | 2009-06 |
授予单位 | 中国科学院研究生院 |
授予地点 | 中国科学院新疆理化技术研究所 |
导师 | 常爱民 |
关键词 | Ntc热敏电阻 共沉淀法 纳米粉体 烧结 导电机理 |
学位名称 | 硕士 |
学位专业 | 微电子与固体电子学 |
英文摘要 | 具有尖晶石相结构的过渡金属(Co、Mn、Ni、Fe、Cu等)氧化物是负温度系数( Negative Temperature Coefficient, NTC)热敏电阻主要的材料体系,具有电阻率随温度升高而降低的特性。由于NTC 热敏电阻灵敏度高,可靠性好,价格低廉 ; Transition-metal (Co、Mn、Ni、Fe etc.) oxides with spinel structure are the most important materials for NTC thermistors, which has the capacity for a wide change in electrical resistance with a change in body temperature. The NTC thermistors are widely used for temperature measurement and control, compensation and suppression of inrush current, due to their high sensitivity to temperature change, high stability and reliability and low price. The Co-Mn-Ni-Fe-O ceramics were used as main materials. The study on preparation provides theoretical basis to prepare NTC thermistors with high-precision, applied to wide temperature range. This dissertaion gave a brief introduction to the history, basic parameters, classification and application of NTC thermistors, at first. The rearch hotspot and trend of NTC thermistors were represented. The effects of solid solution and doping on the properties were analysed. And then, the studies on crystal structure, cation distribution, conductive mechanism of spinel-type NTC thermistor materials as well as their preparation methods were also reviewed. Nano-powders of CoaNi3-b-aMnb-0.5Fe0.5O4 NTC thermistor materials were successfully prepared by co-precipitation method with NH4HCO3 as precipitator, and the reaction process was discussed. When the pH value of the solution is about 8~9, different kinds of cations can be precipitated simultaneously. According to this, the components of the powders can be made closer to the ideal stoichiometry. The samples were characterized by XRD, TG/DTA, FT-IR, SEM, EDS and Laser Particle Size Analyzer. The results show that the powders calcined at 750℃ are single spinel, the grain size of the powders is about 32.1nm, and the particle size is about 78.29nm. When the sintering temperature increase from 900℃ to 1200℃, the porosity decrease, and the density increase from 2.6g/cm3 to 5.1g/cm3.The influences of different sintering processes (the heating and cooling rate, constant temperature) on the microstructure and thermal sensitive characteristics of NTC thermistor materials were investigated. when the process conditions are: constant temperature 840℃ and 1200℃ for 2h respectively, the heating and cooling rate by 1℃/min, the samples possess better electrical properties: ρ25℃ is 1183Ω•cm,B25/50 is 3100K. According to calculating from the slope of lnρ-1/T curves, the activation energy is about 0.26eV. Two groups of samples were prepared: CoaNi3-b-aMnb-xFe-xO4 (0≤x≤0.7) and CocNi3-c-dMnd-xFexO4 (0≤x≤0.4, d-b=0.6) ceramics. The influence of Fe content x changing on the microstructure, density, and electrical properties were studied. The distribution of Fe element in spinel-structure, and conductive mechanism were investigated |
公开日期 | 2014-10-14 |
内容类型 | 学位论文 |
源URL | [http://ir.xjipc.cas.cn/handle/365002/3577] ![]() |
专题 | 新疆理化技术研究所_材料物理与化学研究室 |
推荐引用方式 GB/T 7714 | 张东炎. Co-Mn-Ni-Fe-O NTC热敏电阻材料的制备与性能研究[D]. 中国科学院新疆理化技术研究所. 中国科学院研究生院. 2009. |
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