Y替代对Y<italic>n</italic>(Ba0.8Bi0.2)1-<italic>n</italic>Fe0.9Sn0.1O3负温度系数热敏陶瓷电学性能的影响

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袁昌来, 骆颖, 周秀娟, 杨云, 陈国华, 刘心宇. Y替代对Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃负温度系数热敏陶瓷电学性能的影响 . 无机材料学报, 2014, 29(1): 91-97
YUAN Chang-Lai, LUO Ying, ZHOU Xiu-Juan, YANG Yun, CHEN Guo-Hua, LIU Xin-Yu. Effect of Y Substitution on Electrical Properties of Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃ Negative Temperature Coefficient Thermistor Ceramics . Journal of Inorganic Materials, 2014, 29(1): 91-97 复制到剪切板

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Y替代对Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃负温度系数热敏陶瓷电学性能的影响

袁昌来¹, 骆颖², 周秀娟¹, 杨云¹, 陈国华¹, 刘心宇¹

1. 桂林电子科技大学材料科学与工程学院, 桂林 541004

2. 桂林空军学院, 桂林 541003

袁昌来(1979-), 男, 博士, 高级实验师. E-mail:yclai-2002@163.com

基金:国家自然科学基金青年基金(51102055) National Natural Science Foundation of China (51102055)

摘要

采用传统的固相烧结法制备了Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃负温度系数热敏陶瓷。借助X射线衍射分析仪、扫描电镜、阻温测试仪和交流阻抗分析仪对这类热敏陶瓷的物相、显微结构、阻温特性和阻抗特征进行了表征分析。所得Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃热敏陶瓷为伪立方钙钛矿结构, 粒度约1.0 μm, 随Y含量增加晶格常数a变小; 其室温电阻率、热敏常数和活化能分别介于2.17~9.17 MΩ·cm、6757~7171 K和0.583~0.618 eV范围内, 且均随Y含量增加趋于增大。阻抗分析表明, 在n=0.02、0.04时, 陶瓷体电阻由晶界、晶壳和晶粒电阻构成, 其中晶粒电阻贡献最大; 而在n=0.06、0.08时, 陶瓷体电阻由晶界、畴壁和电畴三个部分构成, 其中电畴区域电阻贡献最大; 在限定的测量温度范围内, 晶界、晶壳、晶粒、畴壁和畴电阻均表现出负温度系数热敏行为。

关键词: 负温度系数热敏陶瓷; Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃; 电学性能; 阻抗分析

中图分类号:TQ174 文献标志码:A 文章编号:1000-324X(2014)01-0091-07

Effect of Y Substitution on Electrical Properties of Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃ Negative Temperature Coefficient Thermistor Ceramics

YUAN Chang-Lai¹, LUO Ying², ZHOU Xiu-Juan¹, YANG Yun¹, CHEN Guo-Hua¹, LIU Xin-Yu¹

1. School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China

2. Guilin Academy of Air Force, Guilin 541003, China

Abstract

Negative temperature coefficient thermistor ceramics based on Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃ were fabricated by conventional solid-state reaction techniques. Phases, microstructures, resistance-temperature curves and impedance characteristics of thermistor ceramics were characterized by X-ray diffraction, scanning electron microscope, resistance-temperature tester and ac impedance analyzer, respectively. Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃ thermistor ceramics with pseudo-cubic perovskite structure show average grain size of ~1.0 μm and the decreasing lattice parametera with increase of Y content. Room-temperature resistivity, thermistor constant and activation energy of thermistor ceramics are in the range of 2.17-9.17 MΩ·cm, 6757-7171 K and 0.583-0.618 eV, respectively. Whenn= 0.02 and 0.04, the ceramic resistance is mainly attributed to the contribution of grain boundaries, grains and grain shells. Among them, the resistance value of grain is the highest one. However, for the ceramics withn= 0.06 and 0.08, the total resistance of thermistor ceramics is ascribed to the contribution of grain boundaries, domain walls and domains, and the domain regions show the larger resistance value than that of the other two elements. In the limited measured temperature range, all of grain boundaries, grain shells, grains, domain walls and domains show negative temperature coefficient thermistor behavior.

Keyword: negative temperature coefficient thermistor ceramics; Y_n(Ba_0.8Bi_0.2)_1-_nFe_0.9Sn_0.1O₃; electrical properties; impedance analysis

Show Figures

负温度系数(negative temperature coefficient, NTC)热敏电阻是一类广泛应用于温度测量及补偿、红外探测和抑制浪涌电流的信息功能材料^{[ 1, 2]}。它们通常是由尖晶石结构的Mn、Ni、Co、Cu、Zn、Al、Mg、Ga等金属氧化物构成^{[ 3, 4, 5, 6, 7]},也有部分以钙钛矿结构的化合物组成, 如BaBiO₃基化合物^{[ 8, 9]}、BaSnO₃基化合物^{[ 10]}、YMnO₃基化合物^{[ 11, 12]}、Sr _xLa_1- _xTi^IV _x₊ _yCo^II _yCo^III_1- _x_-2 _yO₃化合物^{[ 13]}等, 此外还有坡缕石结构的Bi₃Zn₂Sb₃O₁₄ NTC热敏材料^{[ 14]}。在这些材料中, 具有一定铁磁性的尖晶石型NTC热敏材料的导电机理研究得较为透彻, 一般认为是小极化子跳跃机制^{[ 15]}; 而对于钙钛矿结构热敏材料, 其导电机理由于电介质种类的不同而表现各异, 阐明导电机理需要涉及到相变范围和材料内部的电学构件差异等影响。特别是内部构件, 其差异严重地改变介电类材料的内在电学性能, 分析清楚内部构件的组成对阐述电学性能显得至关重要。本工作以新型的钙钛矿结构Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃热敏材料为基体, 借助交流阻抗谱构建电学模型进行研究, 同时分析其宏观阻温特性和微观显微结构特征对电学性能的影响。

1 实验部分

以分析纯Y₂O₃、BaCO₃、Bi₂O₃、SnO₂和Fe₂O₃为原料, 按照Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃化学计量比分别合成 n = 0.02、0.04、0.06、0.08的热敏材料粉体, 预烧温度为850~1000℃, 保温4 h。合成好的粉体在行星球磨机中进行超细粉碎, 烘干, 加入5%浓度的PVA有机粘合剂, 混合均匀, 烘干后用玛瑙研磨磨碎。所得研磨粉体采用内径为18 mm的模具在液压机中压制成圆形生坯体, 将所得生坯体在1040℃下保温4 h烧结成瓷。

采用德国Bruker公司的BRUKERD8- ADVANCE 型X 射线衍射仪(XRD)对样品进行物相与结构分析; 日本JEOL 公司JSM-5610LV 型扫描电子显微镜(SEM)观察样品的微观结构; 华中科技大学的ZWX-C型阻温测试仪(电表为Fluke45)测试直流阻温特性; 采用Agilent 4294A型阻抗分析仪, 在40 Hz~10 MHz频率范围内, 测试了四种含量Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃陶瓷的复阻抗谱。

2 结果与讨论

图1为 n = 0.02、0.04、0.06、0.08的Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃ NTC热敏陶瓷的XRD图谱。从图1可以看出, 四种含量NTC热敏陶瓷均为钙钛矿结构, 在较高角度(55°~58°)出现微弱分峰行为, 表明四种含量NTC热敏陶瓷都显示出接近立方相(伪立方)的钙钛矿结构。此外, 发现存在微弱的第二相衍射峰, 此峰源于Bi₂Fe₄O₉物相。进一步观察图1, 可以发现(110)晶面衍射角随着Y含量增加向高角度稍微迁移, 这意味着Y的加入能使晶格常数 a稍稍变短(见表1), 也表明这四种含量的Y均能完全固熔进该陶瓷体系晶格之中。

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	图1 Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃热敏陶瓷室温XRD图谱Fig. 1 XRD patterns of Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃ thermistor ceramics at room temperature

表1 热敏陶瓷样品的晶格常数 Table 1 Lattice parameter ( a) of the thermistor ceramics

图2给出了 n = 0.04、0.08含量Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃陶瓷的SEM照片。从图2可以看到, 陶瓷晶粒已经形成, 粒度均匀、堆积紧密, 所有晶粒均呈立方柱状, 柱状晶粒大小约1.0 µm, 表明陶瓷已经烧结成瓷。仔细观察还可以发现, 高Y含量的陶瓷晶粒比低Y含量的稍小, 致密度稍差, 表明Y含量变化对陶瓷晶粒大小、致密度和表面形貌产生一定的影响。对于YFeO₃类钙钛矿结构化合物陶瓷, 其成瓷温度高达1400~1500℃^{[ 16]}, 添加Y可以提高陶瓷的最佳成瓷温度, 因而图2的YBBFS4样品陶瓷晶粒比YBBFS2的较小。

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	图2 Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃ ( n=0.04、0.08)热敏陶瓷表面的SEM照片Fig. 2 SEM images of Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃thermistor ceramics ( n=0.04 and 0.08)

图3给出了全部含量的Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃陶瓷的电阻率温度特性图。从图3(a)可以看出, 四种Y含量陶瓷都表现出良好的NTC热敏行为, 图3(b)展示的近线性指数关系则表明这四种Y含量陶瓷都具有良好的NTC热敏效应。这四种Y含量NTC热敏陶瓷对应的室温电阻率( ρ₂₅)、热敏常数( β_25/85)和活化能( E_a)参数总结见表2。从表中可以得出, 这四个Y含量NTC热敏陶瓷的 ρ₂₅、 β_25/85和 E_a分别处于2.17~9.17 MΩ·cm、6757~7171 K和0.583~0.618 eV范围, 且均随着Y含量的增加而增大。Y加入使得 ρ₂₅升高的原因有三个方面: (1) A位中Y³⁺对(Ba²⁺_0.8Bi³⁺_0.2)的部分替代, 为维持电中性, 迫使减少B位Fe⁴⁺的存在几率, 增加Fe³⁺出现几率, Fe³⁺的增多意味着氧空位的相应减少, 而这会导致电阻率的上升; (2) Fe³⁺出现几率的增大, 意味着钙钛矿结构中不稳定的Fe⁴⁺减少, 进而减少八面体位中存在的Fe⁴⁺↔Fe³⁺离子对, 使得载流子传输几率降低, 这也使得电阻率呈现上升态势; (3) Y加入使得陶瓷晶粒尺寸变小且致密度稍差, 降低了载流子间的电子散射时间, 进而导致电阻率上升^{[ 17]}。

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	图3 Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃陶瓷阻温特性曲线 ρ- T (a)和 ρ-1/ T (b)Fig. 3 ρ- T (a) and ρ-1/ T (b) resistivity-temperature curves of Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃ ceramics

表2 Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃热敏陶瓷的组成、 ρ₂₅、 β_25/85和 E_a Table 2 Compositions, ρ₂₅, β_25/85 and E_a of Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃ thermistor ceramics

阻抗谱是一种分析陶瓷内部电学性能构成机制的强有力工具, 可用于半导体、介质、铁电及多铁体材料的内部电学性能研究, 其重要的阻抗和电学模量, 可用来阐明材料的导电、介电损耗和介电机理^{[ 18, 19, 20, 21]}, 阻抗和模量表达式为:

(1)

(2)

其中, ω= 2π f, C₀为真空电容。

基于阻抗和电学模量的Cole-Cole图、 Z"- f和 M"- f图, 以及从Cole-Cole图中获得的各部件电阻、电容与温度关系, 可以准确分析陶瓷体内部各电学部件的导电机制。其中, Z"- f、 M"- f曲线的最强峰分别代表电阻贡献最大的和电容最小的内部部件。通常, 对于半导体陶瓷, 在陶瓷体内部没有出现电化学反应或电极界面效应的情况下, 电容最小部件来自于晶粒的作用并对应于高频区域, 而最高电阻通常来自于晶界并对应于低频区域, 峰对应频率范围介于两者之间的一般表示晶粒壳层。每一个电学构成部件都有对应的电容范围, 晶粒电容( C_g)在10^-11~10^-12F之间, 而晶壳电容( C_gs)和晶界电容( C_gb)对应于10^-8~10^-11F。基于这样的电容和频率范围, 可以分析各个构成部件在Cole-Cole图、 Z"- f和 M"- f图中的对应位置。

图4为YBBFS1热敏陶瓷在三个测试温度下的 Z"- f和 M"- f图谱, 图5为对应Cole-Cole图。从图4可以发现, 在25℃时, Z"- f展现一个高频主峰加一个中频拐点; 当测试温度升至100℃时, 这个拐点趋于弱化, 但低频处出现了一个小峰; 至180℃时, 低频峰变弱, 25℃时的拐点近于消失。三个温度下, M"- f曲线始终只存在高频下的一个强峰。所有的峰及拐点都随测试温度升高向高频移动。观察图5三个测试温度下的Cole-Cole图, 发现低频段始终只有一个圆弧, 中频段在100℃测试时有一个比较明显的圆弧, 而在另外两个温度测试时, 中低频段只有一个圆弧。基于这些分析, 可推测图4各个温度下的主峰和图5的中高频段圆弧由两个部件叠加所致, 而低频下的小圆弧和峰也对应于一个部件。因此可建立如图5(a)插图所示的由多个 RQ构成的等效电路对各个温度下的阻抗进行拟合, 其中 Q为非理想电容, 这是由于满足德拜行为的理想电容很难出现, 因而在阻抗拟合中, 均把理想电容 C替换为 Q。拟合曲线以“━”实线展示在对应的Cole-Cole图中, 对应各部件电容值也在对应Cole-Cole图上。25℃的中高频段和100℃整个频段的拟合较为完整, 25℃的低频段和180℃整个频段拟合曲线不能完全与试验线吻合, 但基本能反映构件的形成趋势, 说明这个等效电路能反映这三个温度下的阻抗所代表的物理现象。基于所得各部件电容大小, 可认为低频下所对应的最大电容为晶界行为; 由于 M"- f唯一峰和 Z"- f高频峰所处频率位置相近, 且电容最小, 可认为此峰源自于晶粒行为; 中频的中等电容则为晶壳行为。拟合所得各部件电阻与1/ T关系展示在图5(b)插图中, 三个部件都表现出近线性指数关系, 即NTC热敏行为, 同时发现晶壳是随温度变化最快的部件。而室温下晶粒是电阻最大的部件, 这点与以前的陶瓷体晶粒行为有所不同^{[ 22]}。对于YBBFS2热敏陶瓷, 也采用了同样的方法进行分析, 拟合结果和构成部件与YBBFS1表现类似, 因而没有继续分析。

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	图4 Y_0.02(Ba_0.8Bi_0.2)_0.98Fe_0.9Sn_0.1O₃陶瓷不同测试温度的 Z"- f和 M"- f曲线Fig. 4 Z"- f and M"- f curves of Y_0.02(Ba_0.8Bi_0.2)_0.98Fe_0.9Sn_0.1O₃ ceramic measured at various temperatures

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	图5 Y_0.02(Ba_0.8Bi_0.2)_0.98Fe_0.9Sn_0.1O₃陶瓷的Cole-Cole图Fig. 5 Cole-Cole plots of Y_0.02(Ba_0.8Bi_0.2)_0.98Fe_0.9Sn_0.1O₃ ceramicThe inset in (a) represents the equivalent circuits in (b) the relation between the components’ resistance and 1/ T

图6为YBBFS3热敏陶瓷的 Z"- f和 M"- f图谱, 图7为对应Cole-Cole图。三个测试温度下, 图6的 Z"- f曲线始终只存在两个峰, 高频段峰的峰频率与 M"- f曲线唯一峰峰频率非常接近, 且峰频随着温度升高向高频移动。基于YBBFS1热敏陶瓷的阻抗分析, 可认为这个高频段的 Z"- f和 M"- f曲线峰归属于陶瓷体的晶粒响应, 低频段的 Z"- f曲线峰为一个电学部件的贡献。按照这种思路, 应组建 R与 Q并联的两个串联 RQ来拟合, 但是, 拟合曲线与实验线差别巨大。假设认为高频段存在一个被叠加的部件, 进而用三个 RQ电学部件进行拟合, 结果仍然不能拟合(这些分析过程本文没有展示), 说明两个或三个串联 RQ的常规分析方法不适合该含量陶瓷, 需要考虑新的电路进行分析。在YBBFS1陶瓷中, 晶粒一直为电阻最大的部件, 这在非铁电体介质材料和半导体陶瓷中是比较反常的。在关于XRD和阻温分析中, 已知Y的加入减少了微量相并提高了体电阻。如果漏电流较小(经检测实际漏电较大), Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃陶瓷理论上应能展现铁电性, 因而推测可能出现了高阻性铁电畴晶粒。基于这种设想, 组建了图7(a)插图所示含有铁电畴晶粒的模拟电路, 其中右下标“dw”代表畴壁, “d”代表铁电畴。基于这样的等效电路进行拟合, 发现三个温度下的拟合结果与实验值相匹配, 表明这种推测的正确性, 反映了Y_0.06(Ba_0.8Bi_0.2)_0.94Fe_0.9Sn_0.1O₃陶瓷体中存在铁电畴和畴壁行为, 但其直观的电畴现象仍需要进一步研究。

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	图6 Y_0.06(Ba_0.8Bi_0.2)_0.94Fe_0.9Sn_0.1O₃陶瓷不同测试温度的Z"- f和M"- f曲线Fig. 6 Z"- f and M"- f curves of Y_0.06(Ba_0.8Bi_0.2)_0.94Fe_0.9Sn_0.1O₃ ceramic measured at various temperatures

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	图7 Y_0.06(Ba_0.8Bi_0.2)_0.94Fe_0.9Sn_0.1O₃陶瓷Cole-Cole图Fig. 7 Cole-Cole plots of Y_0.06(Ba_0.8Bi_0.2)_0.94Fe_0.9Sn_0.1O₃ ceramicThe inset (a) represents the equivalent circuits

在YBBFS4热敏陶瓷阻抗分析中, 基于YBBFS1陶瓷的拟合电路也不能分析, 最后也采用了YBBFS3的拟合电路, 其拟合值以实线见图8(a), 匹配效果比YBBFS3更为完美, 表明增加Y含量提高了电阻率, 改善了陶瓷的铁电性。分析所得的YBBFS3、YBBFS4热敏陶瓷各个部件电阻与1/ T的函数展示在图8(b)中。从图8(b)可以看出, 在YBBFS3、YBBFS4热敏陶瓷中, 铁电畴对陶瓷体电阻的贡献最大, 畴壁次之, 晶界相对较小。铁电畴、畴壁、晶界的电阻与1/ T呈近似线性关系, 表明三个电学构件在此测试温度范围内都具有良好的NTC热敏效应, 并没有出现相变行为, 进而确保存在较好的体相NTC热敏效应。

	Figure Option View Download New Window
	图8 Y_0.08(Ba_0.8Bi_0.2)_0.92Fe_0.9Sn_0.1O₃陶瓷Cole-Cole图(a)和YBBFS3和YBBFS4陶瓷各部件电阻与1/ T关系(b)Fig. 8 Cole-Cole plots of Y_0.08(Ba_0.8Bi_0.2)_0.92Fe_0.9Sn_0.1O₃ ceramic (a) and the relation between the components’ resistance and 1/ T for YBBFS3 and YBBFS4 ceramics (b)

3 结论

1) n = 0.02~0.08时, 能在1040℃烧结成Y _n(Ba_0.8Bi_0.2)_1- _nFe_0.9Sn_0.1O₃陶瓷, 结构分析表明该陶瓷为伪立方钙钛矿结构, Y加入使晶格常数 a稍稍变短, 陶瓷晶粒约为1.0 µm的柱状晶型。

2) 陶瓷的 ρ₂₅、 β_25/85和 E_a分别处于2.17~9.17 MΩ·cm、6757~7171 K和0.583~0.618 eV范围内, 且 ρ₂₅、 β_25/85和 E_a均随着Y含量的增加而升高。

3) 阻抗分析表明, 当 n =0.02、0.04时, 陶瓷体电阻由晶界、晶粒和晶壳三个部分构成, 其中晶粒电阻最大, 晶壳次之, 晶界电阻相对较小; 当 n = 0.06、0.08时, 陶瓷体展现铁电性, 体电阻由铁电畴、畴壁和陶瓷晶界三者联合贡献; 在测试温度范围内, 晶界、晶壳、晶粒、铁电畴、畴壁电阻均表现出NTC热敏行为。

The authors have declared that no competing interests exist.

参考文献

View Option

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4	Park K, Kim S J, Kim J G, et al. Structural and electrical properties of MgO-doped Mn_{1. 4}Ni_{1. 2}Co_{0. 4}-_xMg_xO₄ (0 ≤ x ≤ 0. 25) NTC thermistors. J. Eur. Ceram. Soc. , 2007, 27(4): 2009-2016. [本文引用:1] [JCR: 2.353]
5	Park K. Structural and electrical properties of FeMg_{0. 7}Cr_{0. 6}Co_{0. 7}-_xAl_xO₄ (0≤x≤0. 3) thick film NTC thermistors. J. Eur. Ceram. Soc. , 2006, 26(6): 909-914. [本文引用:1] [JCR: 2.353]
6	Veres A, Noudem J G, Perez O, et al. The effect of manganese substitution to gallium on the physical properties of MgGa₂-_xMn_xO₄ spinel type ceramic thermistors. J. Eur. Ceram. Soc. , 2007, 27(13/14/15): 3873-3876. [本文引用:1] [JCR: 2.353]
7	Park K, Lee J K. The effect of ZnO content and sintering temperature on the electrical properties of Cu-containing Mn_{1. 95-x} Ni_{0. 45}Co_{0. 15}Cu_{0. 45}Zn_xO₄ (0≤x≤0. 3) NTC thermistors. J. Alloys Compd. , 2009, 475(1/2): 513-517. [本文引用:1] [JCR: 2.289]
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13	Feltz A. Perovskite forming ceramics of the system Sr_xLa_1-x Ti^IV_x_{+_yCo^II_yCo^III₁-_x_-2_yO₃ for NTC thermistor applications}. J. Eur. Ceram. Soc. , 2000, 20(14/15): 2367-2376. [本文引用:1] [JCR: 2.353]
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15	Park K, Lee J K. Mn-Ni-Co-Cu-Zn-O NTC thermistors with high thermal stability for low resistance applications. Scripta Mater. , 2007, 57(4): 329-332. [本文引用:1] [JCR: 2.699]
16	Yuan Xueping, Sun Yue, Xu Mingxiang. Effect of Gd substitution on the structure and magnetic properties of YFeO₃ ceramics. Journal of Solid State Chemistry, 2012, 196: 362-366. [本文引用:1] [JCR: 2.159]
17	Park K, Han I H. Effect of Cr₂O₃ addition on the microstructure and electrical properties of Mn-Ni-Co oxides NTC thermistors, J. Electroceram. , 2006, 17: 1069-1073. [本文引用:1] [JCR: 1.194]
18	Yuan C L, Liu X Y, Ma J F, et al. Study on the microstructures and electrical properties of Bi_{0. 5}Ba_{0. 5}Fe_{0. 5}Ti_{0. 49}Nb_{0. 01}O₃ thermistor ceramics. Acta Phys. Sin. , 2010, 59(6): 4253-4260. [本文引用:1] [JCR: 1.027] [CJCR: 1.3886]
19	Yuan C L, Liu X Y, Zhou C L, et al. Characterization of the BaBiO₃-doped BaTiO₃ positive temperature coefficient of a resistivity ceramic using impedance spectroscopy with T_c = 155, Chin. Phys. B, 2011, 20(4): 048701. [本文引用:1]
20	Mu C H, Liu P, He Y, et al. Study on the dielectric properties s and dielectric relaxation of Fe-doped CaCu₃Ti₄O₁₂ ceramics. Acta Phys. Sin. , 2008, 57(4): 2432-2437. [本文引用:1] [JCR: 1.027] [CJCR: 1.3886]
21	Venkataraman B H, Varma K B R. Impedance and dielectric studies of ferroelectric SrBi₂Nb₂O₉ ceramics. J. Phys. Chem. Solids, 2003, 64(11): 2105-2112. [本文引用:1] [JCR: 1.632]
22	Shao S F, Zheng P, Zhang J L, et al. Microstructures and electrical properties of CaCu₃Ti₄O₁₂ ceramics. Acta Phys. Sin. , 2006, 55(12): 6661-6666. [本文引用:1] [JCR: 1.027] [CJCR: 1.3886]

1998

0.711

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... 负温度系数(negative temperature coefficient, NTC)热敏电阻是一类广泛应用于温度测量及补偿、红外探测和抑制浪涌电流的信息功能材料^[1,2] ...

2001

0.0

Int. J. Inorg. Mater.. 2001, 3(8):1215-1217

Preparation and characterization of NiMn₂O₄ films

Schmidt R , Brinkman A W

Thin films of NiMn₂O₄ NTC thermistor material were produced by electron-beam-evaporation from phase pure NiMn₂O₄ source material. The films were characterised using SEM, EDAX, XRD and an Alpha-Step stylus profileometer. Resistance vs. temperature characteristics were obtained over a wide range of temperature and suggested that the conduction mechanism was by variable range hopping. A theoretical model for the thickness profile of the films was derived and comparison of theory with experimental findings showed good agreement.

... 负温度系数(negative temperature coefficient, NTC)热敏电阻是一类广泛应用于温度测量及补偿、红外探测和抑制浪涌电流的信息功能材料^[1,2] ...

2001

2.353

0.0

J. Eur. Ceram. Soc.. 2001, 21(10/11):1783-1785

Controlled thermistor effect in the system Cu_xNi₁-_x_{-_yCo₂_yMn₂-_yO₄}

Vakiv M , Shpotyuk O , Mrooz O

The problem of selection guidelines for oxide semiconducting ceramics with controlled thermistor effect, prepared on the basis of complex Cu_xNi_1–x–yCo_2yMn_2–yO₄ (0.1⩽x⩽0.8; 0.1⩽y⩽0.9–x) chemical system and restricted by CuMn₂O₄, MnCo₂O₄ and NiMn₂O₄ spinel-structured compounds, is discussed. It is shown that the developed ceramic thermistors with a wide range of predetermined exploitation parameters (rated resistance from 2 to 21,500 Ω, material-specific constant B of NTC thermistor from 2435 to 3365 K), as well as a high level of reliability can be obtained using the proper methods of technological, compositional and design modifications. The attempt to establish a general relationships between chemical composition, technological features of sintering and electrical properties for single-phase ceramics is made, using the method of simplex matrices of the 4-fold D-optimum plan.

... 它们通常是由尖晶石结构的Mn、Ni、Co、Cu、Zn、Al、Mg、Ga等金属氧化物构成^[3,4,5,6,7],也有部分以钙钛矿结构的化合物组成, 如BaBiO₃基化合物^[8,9]、BaSnO₃基化合物^[10]、YMnO₃基化合物^[11,12]、Sr_xLa_1-_xTi^IV_x₊_yCo^II_yCo^III_1-_x_-2_yO₃化合物^[13]等, 此外还有坡缕石结构的Bi₃Zn₂Sb₃O₁₄ NTC热敏材料^[14] ...

2007

2.353

0.0

Journal of the European Ceramic Society. 2007, 27(4):2009 - 2016 DOI:10.1016/j.jeurceramsoc.2006.07.002

Structural and electrical properties of MgO-doped Mn_1.4Ni_1.2Co_0.4−xMg_xO₄ (0 ≤ x ≤ 0.25) NTC thermistors

Park K , Kim S J , Kim J G

We have prepared polycrystalline Mn_1.4Ni_1.2Co_0.4−xMg_xO₄ (0 ≤ x ≤ 0.25) samples using a solid-state reaction process and investigated the MgO doping effect on the microstructure and the electrical properties. It was found that, as the amount of Mg content in the Mn_1.4Ni_1.2Co_0.4−xMg_xO₄ samples increased, both the grain size and density decreased. The as-sintered Mn_1.4Ni_1.2Co_0.4−xMg_xO₄ samples contained Mn- and Ni-rich phases with cubic spinel structure. The MgO-doped Mn_1.4Ni_1.2Co_0.4−xMg_xO₄ negative temperature coefficient (NTC) thermistors provided various electrical properties, depending on Mg content. The electrical resistivity,B_25/85 constant, and activation energy of the Mn_1.4Ni_1.2Co_0.4−xMg_xO₄ NTC thermistors increased with increasing Mg content. The values ofρ₂₅,B_25/85 constant, and activation energy of the NTC thermistors were 11,185–20,016 Ω cm, 3635–4032 K, and 0.313–0.348 eV, respectively.

2006

2.353

0.0

J. Eur. Ceram. Soc.. 2006, 26(6):909-914

Structural and electrical properties of FeMg_{0. 7}Cr_{0. 6}Co_{0. 7}-_xAl_xO₄ (0≤x≤0. 3) thick film NTC thermistors

Park K

The microstructure and electrical properties of FeMg_0.7Cr_0.6Co_0.7−xAl_xO₄ (x = 0, 0.1, 0.2, and 0.3) thick film negative temperature coefficient (NTC) thermistors, fabricated by screen printing, were studied. The sintered FeMg_0.7Cr_0.6Co_0.7−xAl_xO₄ bodies were the solid solutions of the constituent oxides along with a small amount of MgAl₂O₄. The electrical resistivity increased with sintering temperature mainly because of an increase in the amount of insulating MgAl₂O₄ resulting from the partial decomposition of the solid solutions during sintering. In addition, the added Al₂O₃ led to a significant increase in the resistivity. The effect of the sintering temperature and Al₂O₃ on the electrical properties of the NTC thermistors was discussed.

2007

2.353

0.0

J. Eur. Ceram. Soc.. 2007, 27(13/14/15):3873-3876

The effect of manganese substitution to gallium on the physical properties of MgGa₂-_xMn_xO₄ spinel type ceramic thermistors

Veres A , Noudem J G , Perez O

Structural, electric and magnetic properties of MgGa_2−xMn_xO₄ based spinel type ceramic compounds have been studied. The samples, prepared by a solid state reaction method, were characterized by X-ray diffraction (XRD), temperature dependent resistivity measurementsρ(T) and magnetic measurementsM(T). Mono-phase solid solutions were obtained for all samples in which magnetic ions interact antiferromagnetically at low temperature. For all samples NTC type behaviour is evidenced. The sensitivity range of these thermistors can be tuned by varying Mn content. The values of the effective magnetic momentum (μ_eff) seem to confirm the well-known electron “hopping” mechanism of electrical conduction, which is believed to act in this kind of materials.

2009

2.289

0.0

J. Alloys Compd.. 2009, 475(1/2):513-517

The effect of ZnO content and sintering temperature on the electrical properties of Cu-containing Mn_{1. 95-x} Ni_{0. 45}Co_{0. 15}Cu_{0. 45}Zn_xO₄ (0≤x≤0. 3) NTC thermistors

Park K , Lee J K

The primary phase of sintered Mn_1.95−xNi_0.45Co_0.15Cu_0.45Zn_xO₄ (0 ⩽ x ⩽ 0.3) bodies was solid solutions of constituent oxides with a cubic spinel structure, along with NiO-rich Mn–Ni–Co–Cu–(Zn)–O oxides and Mn₃O₄. The density and grain size of the Mn_1.95−xNi_0.45Co_0.15Cu_0.45Zn_xO₄ samples increased with increasing ZnO content. The electrical properties of the negative temperature coefficient (NTC) thermistors were controlled by changing their composition. The incorporation of a small amount of ZnO (x ⩽ 0.12) led to an increase in resistivity and theB_25/85 constant. The values ofρ₂₅,ρ₈₅,B_25/85 constant, and activation energy for the NTC thermistors sintered at 1025 °C were somewhat higher than those sintered at 1075 °C. The NTC thermistors with very low resistivities and moderate sensitivities to temperature excursions were fabricated at a wide range of sintering temperature (1025–1075 °C).

2011

2.307

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2007

0.0

2010

2.015

0.0

Journal of Materials Science. 2010, 45(10):2681 - 2687 DOI:10.1007/s10853-010-4249-2

Negative temperature coefficient thermistor based on BaFe_xSn_1?xO_3?ε solid solutions

Changlai Yuan(12) Xinyu Liu(12) Yun Yang(1) Changrong Zhou(1)

1.Guilin University of Electronic Technology Guangxi Key Laboratory of Information Materials 541004 Guilin Guangxi People’s Republic of China
2.Central South University College of Materials Science and Engineering 410083 Changsha People’s Republic of China

A negative temperature coefficient (NTC) thermistors based on BaFe_xSn_1−xO_3−ε were fabricated by conventional solid-state reaction method. The microstructure and electrical properties of the NTC thermistors were characterized by X-ray diffraction (XRD), electric (R(T)), and impedance measurements. The XRD analysis shows that the BaFe_xSn_1−xO_3−ε still remains cubic perovskite structure and the crystal growth orientation changes at higher Fe content. Similarly, the electric measurements indicates that all the samples show typical NTCR behavior; with increasing Fe content, the room temperature resistivity, activation energy, and thermistor constant decrease, are in the range of 2.52–217 KΩ cm, 0.343–0.43 eV, and 3900–4896 K, respectively. The impedance spectroscopy confirms that the observed ac resistance, consisting of the grain bulks, grain boundaries, and electrode–ceramic interface, mainly attributes to the grain boundaries and grain bulks; with the rise in temperature the grain boundary resistance shows more rapid change than the grain resistance; moreover, the Fe concentration can greatly affect the grain and grain boundary resistance.

2002

2.353

0.0

2002

2.353

0.0

2000

2.353

0.0

2003

3.844

0.0

2007

2.699

0.0

Scripta Materialia. 2007, 57(4):329 - 332 DOI:10.1016/j.scriptamat.2007.04.026

Mn–Ni–Co–Cu–Zn–O NTC thermistors with high thermal stability for low resistance applications

A relatively wide range of values of electrical resistivity,B_25/85 constant, and activation energy for Mn_1.95−xNi_0.45Co_0.15Cu_0.45Zn_xO₄ (0 ? x ? 0.3) negative temperature coefficient (NTC) thermistors was obtained by adding ZnO. This means that the electrical properties were adjusted to the desired values, depending on their composition. The incorporation of ZnO up tox = 0.12 led to an increase in both the resistivity and theB_25/85 constant. We successfully fabricated the Zn-added Mn_1.95−xNi_0.45Co_0.15Cu_0.45Zn_xO₄ NTC thermistors with high thermal stability for low resistance applications.

... 在这些材料中, 具有一定铁磁性的尖晶石型NTC热敏材料的导电机理研究得较为透彻, 一般认为是小极化子跳跃机制^[15] ...

2012

2.159

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... 对于YFeO₃类钙钛矿结构化合物陶瓷, 其成瓷温度高达1400~1500℃^[16], 添加Y可以提高陶瓷的最佳成瓷温度, 因而图2的YBBFS4样品陶瓷晶粒比YBBFS2的较小 ...

2006

1.194

0.0

Journal of Electroceramics. 2006, 17(2-4):1069 - 1073 DOI:10.1007/s10832-006-8317-6

Effect of Cr₂O₃ addition on the microstructure and electrical properties of Mn-Ni-Co oxides NTC thermistors

K. Park(1) I. H. Han(1)

1.Sejong University Department of Advanced Materials Engineering Seoul 143-747 Korea Seoul 143-747 Korea

The as-sintered Mn_1.1Ni_1.4Co_0.5O₄ crystallized in the solid solution of cubic spinel Mn-Ni-Co oxides, along with a small amount of the cubic spinel Ni-rich oxide phase. On the other hand, the Cr-substituted Mn_1.1Ni_1.4 Co_0.5−_xCr_xO₄ (0.07 ≤x ≤q 0.35) showed a single phase of cubic spinel Mn-Ni-Co-Cr oxides. This indicates that the substituted Cr suppressed the decomposition in the oxides. In addition, the Cr hindered the grain growth during sintering and increased the porosity. The electrical resistivity, theB_25/85 constant, and the activation energy of the Mn_1.1Ni_1.4Co_0.5−_xCr_xO₄ NTC thermistors increased with increasing Cr content. It is demonstrated that the Cr-substituted Mn_1.1Ni_1.4Co_0.5−_xCr_xO₄ NTC thermistors provided a variety of electrical properties, depending on the composition.

... (3) Y加入使得陶瓷晶粒尺寸变小且致密度稍差, 降低了载流子间的电子散射时间, 进而导致电阻率上升^[17] ...

2010

1.027

1.3886

Acta Physica Sinica. 2010, 59(6):4253 - 4260

Study on the microstructures and electrical properties of Bi_0.5Ba_0.5Fe_0.5Ti_0.49Nb_0.01O₃ thermistor ceramic

Bi_0.5Ba_0.5Fe_0.5Ti_0.49Nb_0.01O₃热敏陶瓷的微结构和电学性能研究

Yuan Chang-Lai, Liu Xin-Yu, Ma Jia-Feng, Zhou Chang-Rong

袁昌来, 刘心宇, 马家峰, 周昌荣

桂林电子科技大学广西信息材料重点实验室,桂林 541004

The Bi_0.5Ba_0.5Fe_0.5Ti_0.49Nb_0.01O₃ thermistor has been prepared by the standard solid-state reaction method, and the microstructures, direct current resistivity, dielectric property, impedance and electric modulus were investigated by the X-ray diffraction, scanning electron microscopy, resistivity-temperature measurement and alternating current impedance spectroscopy. The results show that the material, with an average grain size of about 10 μm, still has cubic perovskite structure, and the lattice constant of the material becomes larger compared with that of the BaTiO₃. The resistivity and thermistor contantB value of the material are about 10⁷ Ω·cm and 7690 K, respectively, and the phase transition occurs twice (at 403 and 523 K), which are confirmed by the dielectric spectrum as a function of temperature. The complex impedance spectroscopy shows the non-ideal Debye type with two incomplete overlapping Cole-Cole semicircles corresponding to the grain and grain boundary resistance. The imaginary part of alternating current resistance as a function of frequency indicates there are two relaxation effects observable in the grain and grain boundary. The phase transition has little effect on the conduction property of bulk grain, but a great impact on that of the grain boundary.

采用固相合成工艺，制备了Bi_05Ba_05Fe_05Ti_049Nb_001O₃（BBFTN）热敏陶瓷，借助X射线衍射仪、扫描电子显微镜、阻温测试仪和交流阻抗谱考察其微结构、直流电阻、介电特性、阻抗和电学模量方面的电学性能. 结果表明：BBFTN材料依然为立方钙钛矿结构，平均晶粒尺寸约为10 μm，晶格常数相对于BaTiO₃的晶格常数有所变大；室温电

... 阻抗谱是一种分析陶瓷内部电学性能构成机制的强有力工具, 可用于半导体、介质、铁电及多铁体材料的内部电学性能研究, 其重要的阻抗和电学模量, 可用来阐明材料的导电、介电损耗和介电机理^{[18,19,20,21]}, 阻抗和模量表达式为: ...

2011

0.0

2008

1.027

1.3886

Acta Physica Sinica. 2008, 57(4):2432 - 2437

Study on the dielectric properties and dielectric relaxation of Fe-doped CaCu₃Ti₄O₁₂ ceramics

Fe掺杂CaCu₃Ti₄O₁₂陶瓷的介电性能与弛豫特性研究

Mu Chun-Hong, Liu Peng, He Ying, Zhang Dan, Meng Ling, Bian Xiao-Bing

慕春红, 刘鹏, 贺颖, 张丹, 孟玲, 边小兵

陕西师范大学物理学与信息技术学院，西安 710062

The CaCu₃Ti_4-xFe_xO₁₂ (0≤x≤0.2) ceramics have been prepared by a standard solid-state reaction method, and the influence of Fe doping on the microstructure and dielectric properties of CaCu₃Ti_4-xFe_xO₁₂ ceramics were investigated by the X-ray diffraction, scanning electron microscopy, dielectric spectroscopy and impedance spectroscopy. It has been found that complete solid solutions are formed for all of the compositionsx. With the increase of Fe content, the semiconductivity of grain vanishes gradually and the dielectric constant decreases. For specimens withx≤0.04, the two dielectric relaxation process Ⅰ and Ⅱappeared in the frequency ranges of 10⁶—10⁸ and 10³—10⁴ Hz, respectively. These two dielectric relaxation process were considered to be associated with grain boundaries and interfacial polarization between the electrode and ceramic surface, respectively. In addition, the third dielectric relaxation Ⅲ was detected in the high-temperature dielectric spectroscopy of CaCu₃Ti_3.99Fe_0.01O₁₂ ceramic, which was caused by a hopping process of localized charge carriers. The activation energy of this thermally excited relaxation is 0.78 eV, as obtained by using the Arrhenius formula.

采用固相反应法制备了CaCu₃Ti_4-xFe_xO₁₂(0≤x≤0.2)陶瓷，通过X射线衍射、扫描电子显微镜、介电频谱和阻抗谱等手段研究了Fe对CaCu₃Ti₄O₁₂陶瓷的结构和介电性能的影响.研究发现：CaCu₃Ti_4-xFe_x

2003

1.632

0.0

2006

1.027

1.3886

Acta Physica Sinica. 2006, 55(12):6661 - 6666

Microstructures and electrical properties of CaCu₃Ti₄O₁₂ ceramics

CaCu₃Ti₄O₁₂陶瓷的微观结构和电学性能

Shao Shou-Fu, Zheng Peng, Zhang Jia-Liang, Niu Xiao-Kun, Wang Chun-Lei, Zhong Wei-Lie

邵守福, 郑鹏, 张家良, 钮效鵾, 王春雷, 钟维烈

山东大学物理系，济南 250100

CaCu₃Ti₄O₁₂ ceramics are prepared by the conventional solid-state reaction method with various sintering temperatures. Microstructures are examined by scanning electronic microscopy, and it is found that they could be categorized into three different types. Dielectric properties and complex impedances are investigated in the frequency range of 40 Hz—110 MHz over a temperature range of 25—280℃. The room temperature dielectric constant increases with sintering temperature. With increasing the measuring temperature, ceramics with different microstructures show diverse electrical properties. However, some common features exist among the electrical properties. For all of the ceramics, dielectric dispersion shows a low-frequency response and two Debye-type relaxations, and there exist three semicircles in the complex impedance plane at high temperatures. The observed electrical properties are ascribed to the detailed internal polycrystalline microstructure, i.e., to come from the contributions of the domains, the grain boundaries and defects inside grains such as domain boundaries, etc.

利用传统的固相反应工艺，在不同的烧结温度下制备了一系列的CaCu₃Ti₄O₁₂陶瓷样品，考察了其微观结构以及介电和复阻抗方面的电学性质.研究发现这些样品在微观结构方面可分为三种类型，高介电性与微观结构有着密切的关联性.室温下，样品的低频介电常数随陶瓷晶粒尺寸的增大而提高.随着测试温度的升高，不同微观结构类型的样品呈现出不同的电学性质的变化，但其中也存在着一些相同的特征.高温下，介电频谱呈现出一个低频介电响应和两个类Debye型弛豫色散，复阻抗谱呈现出三个Cole-Cole半圆弧.将实验上观测到的电学性质的起因归于陶瓷多晶微结构中的晶畴、晶界和晶粒内的缺陷.

... 而室温下晶粒是电阻最大的部件, 这点与以前的陶瓷体晶粒行为有所不同^[22] ...