XJIPC OpenIR  > 材料物理与化学研究室
Ba-Co-O系低温NTC热敏材料制备与性能研究
胡振华
学位类型硕士
导师姚金城
2017-05-25
学位授予单位中国科学院大学
学位授予地点北京
学位专业材料工程
关键词Bacoo3-δ 低温 热敏陶瓷 电阻率 阻温特性
摘要

摘要随着超导技术、航空航天技术、高能物理技术等尖端技术的发展,对低温的测量与控制变得尤为重要。负温度系数(Negative temperature coefficient, NTC) 热敏材料是一种常用的测量温度的材料,在低温测量中也得到了普遍的使用。国内目前的情况下,低温环境下使用的热敏材料还存在一些问题(例如测量低温的极限、工作温区较窄等)。本文的主要研究内容是适用于低温环境的热敏材料与元件的制备与性能研究。本文采用固相反应法,制备了BaCoO3-δ热敏陶瓷材料,并分别研究了掺杂Ni或La元素对作为基体材料的BaCoO3-δ热敏陶瓷结构及电学性能的影响。通过TG/DSC、XRD、SEM、阻温测试、交流复阻抗以及伏安特性测试等手段对制备的热敏陶瓷材料进行了表征与分析,并研究了体系中Ni或La元素的掺杂量对陶瓷材料内部结构、相组成以及低温电学性能的影响及变化规律,并对这些影响的产生进行了解释。主要研究内容如下:(1)采用固相反应法制备了BaCoO3-δ热敏陶瓷材料。XRD分析表明该材料的主要物相是六方钙钛矿相BaCoO2.6 (JCPDS No: 71-2453),有少量的BaO、Co3O4相。结合热敏陶瓷材料的SEM分析和材料的相对密度数据,得出该系列材料的最佳烧结温度为1040 °C,此时的陶瓷致密度高(相对密度为91.74%)。该材料的阻温曲线以26 K为临界点分为两个区域,分别具有典型的负温度系数特性。在12.5 K~26 K区域中,BaCoO3-δ热敏陶瓷电阻率r15 K、B15 K/25 K常数在3397.49~9952.96 Ω?cm、31.15~40.44 K范围内变化。在26 K~100 K区域中,BaCoO3-δ热敏陶瓷热敏电阻的电阻率r30 K、B30 K/50 K常数在749.48~1581.83 Ω?cm、105.26~125.29 K范围内变化。(2)为了提高材料的致密度,鉴于Ni3+(0.06 nm)的离子半径与Co4+(0.053 nm)的离子半径大小接近,在BaCoO3-δ的钙钛矿结构的B位掺杂Ni元素,采用固相法制备了BaNixCo1-xO3-δ(0≤x≤0.1)热敏陶瓷材料。XRD分析表明该材料的主要物相是六方钙钛矿相BaCoO2.6 (JCPDS No: 71-2453),当0≤x≤0.025时没有杂相出现,当0.05≤x≤0.1时有少量的BaNiO3。从BaNixCo1-xO3-δ热敏陶瓷表面的SEM图及该陶瓷材料的密度数据分析可知,x=0.05时的陶瓷在该系列材料中相对密度最大(为96.64%),致密度最高。该材料的阻温曲线以26 K为临界点分为两个区域,分别具有典型的负温度系数特性。该材料的电阻率和材料常数B均随着Ni掺杂量的增加而变大。与BaCoO3-δ材料相比,BaNixCo1-xO3-δ的电阻率r15 K提高了约2个数量级,r30 K提高了约1个数量级。(3)鉴于B位掺杂Ni较大的提高了电阻率(不利于低温环境中的实际应用),为了提高材料的致密度和不至于使得材料的电阻率提高太多,在BaCoO3-δ的钙钛矿结构的A位掺杂La元素,采用固相法制备了LaxBa1-xCoO3-δ(0≤x≤0.1)系列热敏材料。XRD分析表明该材料的主要物相是六方钙钛矿相BaCoO2.6 (JCPDS No: 71-2453),没有杂相出现。从SEM图及陶瓷密度数据分析可知,当La的掺杂量较低时(y=0.025),热敏陶瓷的相对密度为96.62%。该热敏陶瓷的阻温曲线以26 K为临界点分为两个区域,分别具有典型的负温度系数特性。与BaCoO3-δ材料相比,LaxBa1-xCoO3-δ的电阻率ρ15 K提高了约1个数量级,ρ30K提高了约5倍。

其他摘要

AbstractAs the development of the cutting-edge technologies (such as superconducting technology, aerospace technology and high energy physics), the measurement and control of low temperature become more and more important. Negative temperature coefficient (NTC) thermosensitive materials, as a kind of common material for measuring temperature, were also used extensively in the field of low temperature. But in our country, there some problems in the use of heat sensitive materials at low temperature, such as the measurement limitation of the low temperature and the narrow measurement temperature range. The research of this paper is about the preparation and properties of the thermosensitive materials for low temperature. In this paper, BaCoO3-δ thermosensitive ceramics were prepared via solid state reaction method. And the effects of the thermal ceramic structure and electrical properties by the doping of Ni3+ ions or La3+ ions in the matrix material of BaCoO3-δ were also investigated. The ceramic materials were systematically investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), electrical measurement, AC impedance, volt-ampere characteristic and the resistance-temperature properties. The effects of ceramic material microstructures, phase composition and the electrical properties at low temperature by amount of doping elements in the system were also revealed and explained. (1)BaCoO3–δ ceramic materials were prepared via conventional solid state reaction method at different sintering temperatures. The XRD patterns indicate that the major phase presented in the samples is hexagonal perovskite BaCoO2.6 phase and some other minor phases (BaO or Co3O4) were also detected. The SEM images and relative density of the BaCoO3–δ ceramics indicate that the optimum sintering temperature of the material is 1040 ° C, whose relative density is 91.74%.The resistance-temperature curves of the BaCoO3–δ ceramic materials are divided into two ranges by 26 K. It is obviously that the resistivities of the BaCoO3–δ ceramic termistors decreased exponentially with increasing temperature in each of the range, respectively. Which is the typical negative temperature characteristic. In the 12.5 K~26 K range, the obtained r15 K, B15 K/25 K constant of the BaCoO3–δ thermistors are in the range of 3397.49~9952.96 Ω?cm and 31.15~40.44 K, respectively. In the 26 K~100 K range, the obtained r30 K, B30 K/50 K constant the BaCoO3–δ thermistors are in the range of 749.48~1581.83 Ω?cm and 105.26~125.29 K, respectively.(2)In order to improve the density of the material, Ni ions were doped at the B site of perovskite structure of BaCoO3-δ ceramics because the radius of Ni3+ (0.06 nm) is close to the radius of Co4+ (0.053 nm). BaNixCo1-xO3-δ(0≤x≤0.1)ceramic materials were prepared via conventional solid state reaction method. The XRD patterns indicate that the major phase presented in the sintered samples is hexagonal perovskite BaCoO2.6 phase. There are no minor phase when 0≤x≤0.025, but minor phase BaNiO3 was detected when 0.05≤x≤0.1. When x=0.05, the SEM images and relative density of the BaNixCo1-xO3-δ(0≤x≤0.1) ceramics indicate the density of the ceramics is the biggest , whose relative density is 96.64%. The resistance-temperature curve of the BaNixCo1-xO3-δ ceramic materials is divided into two ranges by 26 K. It is obviously that the resistivities of the BaNixCo1-xO3-δ ceramic thermistors decreased exponentially with increasing temperature in each of the range, respectively. Which is the typical negative temperature characteristic. In the 12.5 K~26 K range, the obtained r15 K, B15 K/25 K constant of the BaNixCo1-xO3-δ thermistors are in the range of 4.06×103~5.15×105 Ω?cm and 34.46~59.08 K, respectively. In the 26 K~100 K range, the obtained r30 K, B30 K/50 K constant the BaNixCo1-xO3-δ thermistors are in the range of 77.95×103~ 3.62×104 Ω?cm and 134.42~240.57 K, respectively. The resistivities and material constant B of the material increase with the increase amount of Ni doped in the matrix. Compared with BaCoO3–δ materials, the resistivity of ρ15 K and ρ30 K of BaNixCo1-xO3-δ thermistors increase by about two or one orders of magnitude, respectively.(3)The application of the ceramics at low temperature are adversely affected by the doping of Ni ions at B site because of the significant increase of the resistivity of ceramics. In order to improve the density of the material and not to increase the resistivity significantly, La ions were doped at the A site of perovskite structure of BaCoO3-δ ceramics. LaxBa1-xCoO3-δ(0≤x≤0.1)ceramic materials were prepared via conventional solid state reaction method. The XRD patterns indicate that the major phase presented in the samples is hexagonal perovskite BaCoO2.6 phase and there are no minor phases were detected. LaxBa1-xCoO3-δ(0≤x≤0.1)ceramic materials were prepared via conventional solid state reaction method. When x=0.025, the SEM images and relative density of the LaxBa1-xCoO3-δ(0≤x≤0.1)ceramics indicate the density of the ceramics is the biggest, whose relative density is 96.62%.The resistance-temperature curves of the LaxBa1-xCoO3-δ ceramic materials are divided into two ranges by 26 K. It is obviously that the resistivities of the BaNixCo1-xO3-δ ceramic thermistors decreased exponentially with increasing temperature in each of the range, respectively. Which is the typical negative temperature characteristics. In the 12.5 K~26 K range, the obtained r15 K, B15 K/25 K constant of the BaNixCo1-xO3-δ thermistors are in the range of4.06×103~6.61×104 Ω?cm and 34.46~62.45 K, respectively. In the 26 K ~ 100 K range, the obtained r30 K, B30 K/50 K constant the BaNixCo1-xO3-δ thermistors are in the range of .95×102~3.66×103 Ω?cm、134.43~188.39 K, respectively. The resistivities of the material and material constant B increase with the increase amount of Ni doped in the matrix. Compared with BaCoO3–δ materials, the resistivity of ρ15 K and ρ30 K of BaNixCo1-xO3-δ thermistors increase by about one or half of one order of magnitude, respectively.

文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/4945
专题材料物理与化学研究室
作者单位中国科学院新疆理化技术研究所
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胡振华. Ba-Co-O系低温NTC热敏材料制备与性能研究[D]. 北京. 中国科学院大学,2017.
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