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Zn掺杂制备Ni (Co)-Mn基高稳定性NTC热敏氧化物材料及其性能研究
Thesis Advisor常爱民
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline微电子学与固体电子学
KeywordZn元素掺杂 相结构 Ntc热敏陶瓷 热稳定性

在NTC热敏电阻领域,含Mn尖晶石结构热敏陶瓷具有悠久的应用历史,其中Mn、Ni、Co是被使用最多的元素。Ni-Mn-O体系氧化物材料则是实际应用最多的体系,具有很高的实用价值。另外Co-Mn-O基氧化物材料具有较高的B值、低的电阻率。而Fe元素可以显著地增加材料的电阻率,所以Fe-Co-Mn-O体系将会具有高的电阻率以及高的B值。为了制备具有特定目标参数的NTC热敏电阻,本文选用Zn元素对Ni-Mn-O以及Fe-Co-Mn-O材料体系进行掺杂实验。通过材料组分以及制备工艺的优化来制备具有特定目标参数的NTC热敏电阻。制备了三元系ZnxNi1-xMn2O4(0≤x≤1.0)和四元系ZnxFea-xCo2MnbO8(0≤x≤0.8, a+b=4)系列陶瓷,通过激光粒度分析、X射线衍射分析、扫描电子显微镜测试、热膨胀测试、交流复阻抗测试、电阻温度关系测试等方法,研究了Zn元素掺杂对含Mn系尖晶石型NTC热敏陶瓷的性能研究。主要研究内容如下:(1)采用氧化物固相球磨法制备ZnxNi1-xMn2O4(0≤x≤1.0)系列NTC热敏陶瓷。1200 oC烧结后陶瓷的X射线衍射分析结果表明:当0≤x≤0.4,陶瓷为单一的立方尖晶石相;当x=0.6, 0.8时,样品由立方尖晶石和四方尖晶石相共同构成;而当x=1时,陶瓷由单一的四方相组成。(2)电学性能测试结果表明,ZnxNi1-xMn2O4陶瓷的电阻率随Zn含量的增加而呈现V字型变化,室温电阻率范围为:3143-136780 Ω.cm,材料常数范围为:3893-4491K。当x=0.25时电阻率最小,即ρ25=3143Ω.cm。(3)该系列陶瓷在125oC老化500 h后,电阻率漂移率在0.69%-1.72%范围内。其中x=0.25对应的材料组分表现出较高的热稳定性。(4)采用液相共沉淀法,制备出ZnxFea-xCo2MnbO8(0≤x≤0.8)系列NTC热敏陶瓷。EDS能谱分析结果表明:各种金属元素都已完全沉淀。高温烧结后各组分陶瓷都具有单一的立方尖晶石结构。(5)随着Zn含量的增加,ZnxFea-xCo2MnbO8(0≤x≤0.8)陶瓷的电阻率先减小后增大,在x=0.6时电阻率最小。室温电阻率范围为:9.7-27kΩ.cm,材料常数范围为:3966-4270K。(6)本文通过对Zn0.4Fea-0.4Co2MnbO8陶瓷制备工艺的优化,最终在1200oC烧结以及慢速退火等制备条件下,成功制备出具有目标参数的NTC热敏电阻。

Other Abstract

The Mn based spinel NTC ceramics have a long history in the NTC thermistors field, and Mn, Ni and Co are the most used elements. And the Ni-Mn-O is the most used system. Besides, the Co-Mn-O system has higher B constant and lower resistivity. The resistivity could be increased by adding Fe into the Co-Mn-O system. So the Co-Mn-Fe-O is likely to have high B constant and high resistivity, and is promising in the application of household appliances. We chose the Zn element as dopant to be added to the Ni-Mn-O system and Co-Mn-Fe-O system. In order to prepare the NTC thermistors with the target parameters, we studied the different composition and improved the preparation processes. In this paper, the effects doping with Zn ions on the microstructure and electrical properties of Ni1-xZnxMn2O4 (0≤x≤1.0) and Co2MnbFea-xZnxO8 (0≤x≤0.8, a+b=4) NTC ceramics were investigated. The specific results are as follows: (1) The Ni1-xZnxMn2O4 (0≤x≤1.0) NTC ceramics were prepared by the traditional solid state reaction method. X-ray diffraction (XRD) results show that the as-sintered ceramics transformed to tetragonal spinel (x=1) gradually from cubic spinel (x=0). (2) The as-sintered ceramics exhibited the typical characteristics of NTC thermistors. The electrical resistivity decreased slightly then increased dramatically with the increasing of Zn content, and the ρ25 is in the range of 3143-136780 Ω.cm. The ρ25 has the minimum value at x=0.25. (3)The relative resistance drift △R/R0 was in the range of 0.69%-1.72% after aging test at 125 oC for 500 h. The lowest resistivity and highest stability were found at Ni0.75Zn0.25Mn2O4 ceramic simultaneously. (4) The Co2MnbFea-xZnxO8 (0≤x≤0.8) NTC ceramics were prepared by co-precipitation method. The EDS results show that all the metal cations were precipitated. The electrical resistivity decreased with the adding of Zn for 0≤x≤0.6, but increased for x=0.8. (5) The electrical drift of Co2MnbFea-0.4Zn0.4O8 ceramic annealed with low cooling speed, is as low as 0.05%, but that with high cooling speed is 0.21%. (6) We selected the Co2MnbFea-0.4Zn0.4O8 composition and optimized the preparing processes. As sintered at 1200 oC and annealed with low cooling speed, the Co2MnbFea-0.4Zn0.4O8 NTC ceramics obtained the target parameters.

Document Type学位论文
Recommended Citation
GB/T 7714
程飞. Zn掺杂制备Ni (Co)-Mn基高稳定性NTC热敏氧化物材料及其性能研究[D]. 北京. 中国科学院大学,2015.
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