本文關(guān)鍵詞： NTCR 鈣鈦礦結(jié)構(gòu) 摻雜 室溫電阻率 B值 溫度區(qū)間　出處：《西安電子科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：NTCR由于具有負(fù)系數(shù)的阻溫特性以及體積小、可靠性強(qiáng)、靈敏度高、成本較低等優(yōu)點(diǎn),被廣泛的應(yīng)用在電子產(chǎn)品的過(guò)流保護(hù)、測(cè)溫控溫和溫度的補(bǔ)償?shù)冗^(guò)程中,已成為航空航天、儀器儀表等領(lǐng)域不可缺少的電子元器件之一。隨著科技進(jìn)步,對(duì)工作在某些惡劣環(huán)境中電子元器件的性能有了更嚴(yán)格的要求,其中就包括高溫NTC熱敏電阻的開發(fā),這就要求材料具有高阻值低B值的基本性質(zhì),而傳統(tǒng)的NTC熱敏電阻采用尖晶石結(jié)構(gòu),但是這種結(jié)構(gòu)在高溫下穩(wěn)定性并不是很好。研究發(fā)現(xiàn),鈣鈦礦結(jié)構(gòu)的稀土錳氧化物型具有NTC效應(yīng),且鈣鈦礦結(jié)構(gòu)緊密,穩(wěn)定性強(qiáng),但其室溫電阻率非常小。因此本文采用LaMnO_3為材料導(dǎo)電的主體結(jié)構(gòu),與尖晶石結(jié)構(gòu)的高溫固溶相MgAl_2O_4進(jìn)行兩相的復(fù)合,通過(guò)兩相調(diào)節(jié)和元素的摻雜,采用高溫固相法制備NTC熱敏元件。首先探索兩相粉末樣品的燒結(jié)工藝,分別在幾個(gè)溫度下對(duì)粉體進(jìn)行高溫預(yù)燒,經(jīng)過(guò)XRD衍射分析,在1200℃成功制備出LaMnO_3粉末樣品,在1300℃制備出MgAl_2O_4粉末樣品。粉體樣品制備成功后,又研究在LaMnO_3相內(nèi)引入MgAl_2O_4帶來(lái)的影響,經(jīng)過(guò)幾組實(shí)驗(yàn)對(duì)比發(fā)現(xiàn)MgAl_2O_4的引入提高了元件的電阻率和B值。為了得到合適的室溫電阻率,我們調(diào)節(jié)兩相的比例,得到MgAl_2O_4和LaMnO_3的摩爾比例為0.3-0.7時(shí)較為合適。另外,我們將元件進(jìn)行了弱還原氣氛中的熱處理,以及再次在空氣中的升溫,經(jīng)測(cè)試,元件阻值先明顯增大然后又基本恢復(fù)熱處理前的水平,可以說(shuō)明這種復(fù)合體系的元件是p型導(dǎo)電的。然后,在0.3 MgAl_2O_4-0.7 LaMn O_3體系的基礎(chǔ)上,通過(guò)在LaMnO_3的Mn位也就是鈣鈦礦結(jié)構(gòu)的B位進(jìn)行Cr~(3+)、Al~(3+)和Ti~(4+)的摻雜,研究摻雜元素對(duì)元件室溫電阻率和B值以及使用溫區(qū)拓展情況的影響。實(shí)驗(yàn)結(jié)果表明,Cr~(3+)和Al~(3+)在B位的摻雜都可以使晶粒尺寸細(xì)化,同時(shí)晶界增多,氣孔率也有所增加,使得元件電阻率和B值有所增大,0.3 MgAl_2O_4-0.7 LaMn_(0.5)Cr_(0.5)O_3體系的使用溫區(qū)拓寬到445℃。Ti~(4+)的高價(jià)摻雜不僅抑制晶粒晶界生長(zhǎng),且稀釋了離子導(dǎo)電對(duì)濃度,B位摻雜量超過(guò)0.4時(shí),摻雜效果減弱,使得元件室溫電阻率大幅度上升。
[Abstract]:The NTCR resistance temperature characteristic with negative coefficient, small size, high reliability, high sensitivity, low cost, is widely used in the current protection of electronic products, such as process monitoring and controlling temperature compensation in mild temperature, has become one of the indispensable components of aerospace, electronic instrumentation and other fields. With the progress of science and technology the performance of the work, in some harsh environments of electronic components have more stringent requirements, which includes the development of high temperature NTC thermistor, which requires the basic properties of materials with high resistance and low B value, NTC thermistor and traditional with spinel structure, but the structure is not very stable at high temperature good. The study found that rare earth manganese oxide perovskite structure with NTC effect, and the perovskite structure closely, strong stability, but the resistivity at room temperature is very small. So this paper uses LaMnO_3 to The main structure of the conductive material, and high temperature spinel solid solution phase of MgAl_2O_4 composite phase, the phase adjustment and doping, preparation of NTC thermistor by high temperature solid-state method. Firstly, the exploration on sintering process of powder samples of two-phase, powder at several temperatures high temperature calcination, through XRD diffraction analysis in 1200 C prepared LaMnO_3 powder samples, 1300 degrees in the preparation of MgAl_2O_4 powders. Powders were successfully prepared, and research into the influence of MgAl_2O_4 in the LaMnO_3 phase, after several experiments showed that MgAl_2O_4 can improve the resistivity and B value of the components. In order to get the appropriate resistivity at room temperature, we adjust the ratio of phase, the molar ratio of MgAl_2O_4 and LaMnO_3 by 0.3-0.7 was suitable. In addition, we will be components of a weak reducing heat in the atmosphere, and Again in the air temperature, the test element resistance increases first and then returned to the level before the heat treatment, that this composite element is p conductive. Then, based on the 0.3 MgAl_2O_4-0.7 LaMn O_3 system, through the LaMnO_3 Mn is a perovskite structure of B Cr~ (3+), Al~ (3+) and Ti~ (4+) doping of doping elements on the components of the room temperature resistivity and B value and expand the influence of using temperature. The experimental results show that Cr~ (3+) and Al~ (3+) in B doping can make the grain size refinement and grain boundary increased porosity also increased, the element resistivity and B value increased, 0.3 MgAl_2O_4-0.7 LaMn_ (0.5) Cr_ (0.5) use the O_3 system to broaden the temperature to 445 DEG C.Ti~ (4+) high doping not only inhibit the grain growth of the grain boundary, and the dilution of the concentration of ion conductive, B doping When the doping effect is less than 0.4, the room temperature resistivity increases greatly.

【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN37

【引證文獻(xiàn)】

相關(guān)期刊論文 前1條

1 閻家光;;NTC熱敏電阻在防止啟動(dòng)電流過(guò)流中的應(yīng)用[J];電子技術(shù)與軟件工程;2017年16期

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本文編號(hào)：1444442