【作者】 黄振兴；

【导师】 邓昭平； 杨敬义；

【作者基本信息】 成都理工大学 ， 材料学， 2011， 硕士

【摘要】 钛酸钡基陶瓷材料在居里点Tc之前呈现良好的NTC特性,关于BaTiO3陶瓷在NTC特性及其机理方面的研究,迄今国内外很少见报导,是一个比较新的研究方向。钛酸钡基NTC功能陶瓷有着广阔的市场应用前景和重要的研究价值。根据氧化物半导体理论获得高电阻率、低B值材料是困难的。为满足物联网、汽车电子、各种半导体器等对宽温区温度补偿和测温应用急剧增长的需要,因此要求NTC热敏材料实现高电阻值、低B值。而采用常规的热敏材料配方是无法实现的。高电阻值、低B值热敏材料己成为当今负温度系数热敏电阻制造的一大难题。本实验采用固相合成法合成BaTiO3基NTC热敏陶瓷电阻材料,通过添加Pb以提高材料的居里点,以扩大NTC元件的工作温度范围,研究探索其NTC温度范围内其实现高电阻值、低B值特征的可能性；掺杂Nb205以提高半导化程度,降低材料的电阻率；添加BN做助烧剂,降低烧结温度。本文主要研究了烧结工艺与配方对BaTiO3基NTC热敏陶瓷材料的影响,并就线性NTC及高电阻率低B值的NTC材料做了研究。主要结论如下：(1)烧结温度对NTC材料的性能有很大影响,室温电阻率ρ25与烧结温度呈U型关系,本实验中,烧结温度在1180℃时,样品性能较好,为样品的较佳烧结温度。烧结中对样品进行适当的保温有利于助于晶粒半导化,降低室温电阻值,本实验中,保温1h时室温电阻率较小,样品的NTC性能也较好；(2)Pb能有效提高材料的居里点,扩大材料的工作温度范围。本实验中,居里点T。最高达330℃。同时,Pb的掺杂可以降低材料的电阻率,提高半导化程度；(3)BN是一种非常有效的助烧剂,能有效降低烧结温度,BN越多烧结温度越低。少量BN和Nb205的加入能提高材料的半导化程度,降低材料的电阻率,实验中BN为2mo1%时室温电阻率较低,ρ25=35.7Ω·cm。同时证实了Nb205有抑制晶粒生长的作用；(4)实验所得样品,电阻率为1316.7Ω·cm,B值为954.1,属于典型的高电阻率、低B值的NTC热敏电阻,且Tc为330℃,工作温度范围较大,具有良好的应用前景。更多还原

【Abstract】 At temperature below the Curie point, the BaTiO3-based ceramics presents g ood character of NTC (Negative Temperature Coefficient). The NTC character of BaTiO3-based ceramics is rare studied and reported. High room temperature re sistivity (ρ25) and low B constant thermistors have a broad market application perspective, widely used for temperature measurement and compensation, inrush current limiting, etc. But according to the semi-conduction theory, it is hard t o synthesis using the traditional methods.The aim of this work is to synthesis and study highρ25 and low B consta nt BaTiO3-based NTC ceramic thermistors. Solid-phase synthesis is used, addin g Pb to shift the Curie point, doping ND2O5 to semi-conduct materials and low erρ25, and doping BN to reduce sintering temperature. The influence of proces s and formulas is studied on the BaTiO3-based NTC materials. Main conclusio ns follow as:(1) Sintering temperature has a major effect on the materials. The relations hip ofρ25 and sintering temperature is U-shape. Samples show better NTC cha racter at sintering temperature 1180℃. Appropriate time of heat preservation te mperature helps materials semi-conducting. During this experimentρ25 is minim um when the time of heat preservation is 1h(2) Pb doping is effective for shifting the Curie point. When Pb=60mol%, the Curie point is 330℃which is a lot increment compare to the pure BaTi O3 materials. (3) BN can reduce the sintering temperature, also help semi-conduction. W hen BN=2mol%, samples’=35.7Ω·cm. Nb2O5 promotes semi-conduction and 1o werρ25. Also it can inhibit grain growth.(4)ρ25 of synthesized samples is above 1.3k and constant B is below 1k. It is typical highρ25 and low B NTC thermistor. The Curie point is 330℃, s howing good application perspective.更多还原