共查询到18条相似文献,搜索用时 171 毫秒
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Y和YF3掺杂钛酸钡系PTCR材料的结构及性能 总被引:1,自引:0,他引:1
在不同烧结气氛下制备了Y和YF3掺杂钛酸钡材料,借助于XRD、SEM、XRF和阻温测试分析仪,研究了烧结气氛对Y和YF3掺杂钛酸钡材料结构和性能的影响.研究结果表明,低氧分压气氛可促进Y和YF3掺杂钛酸钡材料的烧结,晶粒长大,而且这二种掺杂钛酸钡材料都是n型半导体.经过氩气气氛烧结的Y掺杂钛酸钡材料PTCR效应较弱;而对在氩气气氛中烧结的0.3mol%YF3掺杂钛酸钡材料却观察到了较好的PTCR效应,这种效应的产生可能与F元素取代O位而导致材料的价控半导有关. 相似文献
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掺杂V2O3素PTC陶瓷中金属相的研究 总被引:1,自引:1,他引:0
报导在掺杂V2O3系PTC陶瓷中引入Fe金属相,采用XRD,SEM分析技术确定Fe金属相在材料中的结构状态,并结合材料PTC性能测试结果讨论了Fe金属相对材料烧结性能和PTC性能的影响。 相似文献
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Y(NO3)3掺杂BaTiO3半导体材料特性研究 总被引:2,自引:0,他引:2
本文研究了以Y(NO3)3作为施主掺杂元素制备的PTCR材料的显微结构和宏观性能。指出施主以水溶性化合物形式引入制备的PTCR材料,其性能明显优于常规的施主以氧化物形式引入而得到的材料的性能。 相似文献
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采用固相烧结工艺制备出了Sr0.4Pb0.6TiO3半导体陶瓷元件,其阻温特性具有独特的NTCR和PTCR复合效应,陶瓷室温电阻率及居里点以下的NTCR效应随着烧结温度的升高而提高,适当过量PbO则能降低陶瓷室温电阻率及其NTCR效应.利用XRD、SEM和EDS分别对样品的相结构、形貌及成份分布等进行分析,结果显示晶界中的Sr,Ti含量相对较高,而Pb含量相对较低,材料的阻温特性明显受其影响.铅挥发造成的阳离子空位是该类半导体陶瓷在居里点下出现NTCR效应的主要原因之一,同时探讨了Y3+离子掺杂(Sr,Pb)TiO3陶瓷的半导化机理和热敏特性. 相似文献
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Sol—Gel法制备Y系高温超导材料及烧结条件的研究 总被引:1,自引:0,他引:1
介绍了YBa2Cu3O7-δ和F掺杂的YBa2Cu3F0.6O7-δ高Fc超导材料的Slo-Gel法制备,并对烧结条件进行了研究。 相似文献
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在制备高质量的(Ba,Pb)TiO_3基高居里温度PTCR陶瓷时,一般采用铅气氛烧结方法。但是,这种烧结工艺制成的产品的相对成本是高的。作者的实验表明,高容量SiO_2掺杂烧结方法也可以用于制备高质量的(Ba,Pb)TiO_3基高居里温度PTCR陶瓷。本文主要报道高容量SiO_2对(Ba,Pb)TiO_3基高居里温度PTCR陶瓷烧结工艺和电特性的影响。 相似文献
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J.-G. Kim W.-P. Tai Y.-J. Kwon K.-J. Lee W.-S. Cho N.-H. Cho C.M. Whang Y.-C. Yoo 《Journal of Materials Science: Materials in Electronics》2004,15(12):807-811
Donor doped BaTiO3 (n-BaTiO3) ceramics were fabricated by adding polyethylene glycol (PEG) at 20 wt %. The effects of reducing and oxidizing atmospheres on the PTCR characteristics of the porous n-BaTiO3 ceramics were investigated. The PTCR characteristics of the porous n-BaTiO3 ceramics is strongly affected by chemisorbed oxygen at the grain boundaries and are recovered as the atmosphere is changed from the reducing gas to oxidizing gas. The low room-temperature resistivity of the porous n-BaTiO3 ceramics in reducing atmospheres may be caused by the decrease in potential barrier height, which originates from an increase in the number of electrons owing to the desorption of chemisorbed oxygen atoms at the grain boundaries. In addition, the high room-temperature resistivity of the porous n-BaTiO3 ceramics in oxidizing atmospheres may be caused by the increase in potential barrier height, which results from the adsorption of chemisorbed oxygen atoms at the grain boundaries. 相似文献
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为了探索利用EPR谱线对PTCR陶瓷相变及PTC效应的机制研究的可能性,本文对掺Mn的BaTiO3基正温度系数热敏电阻(简称PTCR)陶瓷在120-450K温度范围内的电子顺磁共振谱进行了研究。得于了Mn^2 离子EPR信号强度、g因子值和超精细耦合常数|A|值的温度分布,发现EPR参数与PTCR陶瓷相变有明显的对应关系,并给出微观结构上的初步解释。研究表明EPR谱线以及精细结构的分析可以为PTCR陶瓷的相变机制以及上的初步解释。研究表明EPR谱线以及精细结构的分析可以为PTCR陶瓷的相变机制以及PTC效应的机制研究提供新的途径。 相似文献
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Effect of atmosphere on the PTCR properties of BaTiO3 ceramics 总被引:1,自引:0,他引:1
The influence of low-temperature annealing, at < 360 °C, in various reducing and oxidizing atmospheres for a series of BaTiO3 ceramics with a positive temperature coefficient of resistance (PTCR) is discussed. Combined impedance and modulus spectroscopy is used to analyse a.c. impedance data and shows that the total resistance of the sample can be composed of up to three components, dependent on the cooling rate from the sintering temperature. For quickly cooled samples the PTCR response is dominated by an outer shell on individuals grains, whereas for slowly cooled samples the grain boundary resistance dominates. Annealing in reducing atmospheres destroys the grain boundary PTCR effect whereas the outer-shell grain PTCR effect is relatively insensitive to the reducing atmosphere. It is proposed that the acceptor states responsible for the outer-grain and grain-boundary PTCR effects are predominantly intrinsic metal vacancies, i.e. Ba and/or Ti, and adsorbed oxygen, respectively. 相似文献
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The electrical properties of donor (La3+) doped BaTiO3 samples with a donor concentration in the range from 0.3 to 1.5 mol.% of La were studied. Samples were sintered at a low partial pressure of oxygen in order to facilitate anomalous grain growth and donor incorporation. In order to optimise the PTCR anomaly, the samples were annealed in air at 1100°C. Results show that with the use of a specific sintering profile PTCR ceramics containing an amount of donor dopant >0.3 mol.%, can be prepared. Heavily doped samples which do not exhibit anomalous grain growth show a core shell structure. 相似文献
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Xuxin Cheng Dongxiang Zhou Qiuyun Fu Shuping Gong Dongchen Zhao 《Journal of Materials Science: Materials in Electronics》2012,23(12):2202-2209
The effects of the Nb-dopant content and the sintering conditions on the electrical properties and the positive temperature coefficient of resistance (PTCR) effect of Ba1.005(Ti1?xNbx)O3 (BTN) ceramics were investigated, which were sintered at 1,070–1,220?°C for 0.5–6?h in a reducing atmosphere and then re-oxidized at 600–750?°C for 1?h. The results indicated that both the sintering temperature and sintering time affected the electrical properties and the PTCR effect of the multilayer BTN samples, whose room-temperature (RT) resistance first reduced and then increased as a function of the donor–doped concentration at all sintering temperature; moreover, the higher the sintering temperature was, the lower the critical dopant concentration. The BTN ceramics showed a remarkable PTCR effect, with a resistance jump greater by 3.3 orders of magnitude, along with a low RT resistance of 0.3?Ω at a low reoxidated temperature of 600?°C after sintering in a reducing atmosphere. 相似文献
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Qiu-yun Fu Yu-xiang Qin Dong-xiang Zhou Yun-xiang Hu Zhen-zhen Xie 《Journal of Materials Science: Materials in Electronics》2013,24(3):987-992
BaTiO3 ceramics for positive temperature coefficient resistance (PTCR) were fabricated via tape casting technique and reduction/reoxidation process. A novel method was used to regulate the density of the ceramics via changing binder amount in tape casting green bodies. The influences of different amounts of the binder on density, electrical properties, and microstructure of ceramics were investigated. The BaTiO3 ceramic monolith without internal electrodes with an addition of binder of 0.84 wt% was sintered in reducing atmosphere at 1150 °C and reoxidized at 800 °C for 1 h showed a resistivity of 56 Ω·cm and a PTCR jump about 3.2 orders of magnitude. The green and sintered density of the samples decreased with the increasing binder amount. The room temperature resistivity increased monotonically with the binder amount. However, the correlation of the PTCR jump with binder amount showed a contrary tendency. These electrical properties can be explained by the Jonker model. The influences of sintering temperature on the density of BaTiO3 ceramics with different binder amount were also discussed. In addition to the ceramic monoliths without internal electrodes, multilayer elements with internal electrodes were also prepared. 相似文献