异价元素扩散掺杂对磁控溅射法制备的GDC薄膜电导行为的影响

发布时间：2018-03-13 01:01

  本文选题：磁控溅射　切入点：GDC薄膜　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：相比传统的氧离子导体固态电解质Y掺杂的稳定Zr02(YSZ),Gd掺杂的Ce02(GDC)因其在中温条件下具有更高的电导率而被广泛研究。为了满足电解质材料薄膜化、中温化的发展趋势,对GDC电解质的制备工艺以及电导性能的研究显得越来越重要。本论文采用反应直流磁控溅射法在单晶A1203基片上制备了 GDC薄膜,XRD物相分析结果表明磁控溅射法制备的GDC薄膜具有立方萤石结构,沿(111)面择优生长。SEM形貌观察结果显示GDC薄膜具有典型的柱状晶结构,薄膜与基片结合力良好。TEM分析结果表明不同退火温度下GDC薄膜晶粒尺寸在10 nm到100 nm之间。采用溶胶-凝胶法制备了含Fe和Si元素的溶胶,将溶胶涂覆在GDC薄膜表面,再通过热扩散工艺将Fe元素和Si元素掺杂到晶界处,对GDC薄膜的能谱分析表明GDC薄膜的晶界处含有硅质相,而掺杂的Fe元素能够改变晶界处硅质相的润湿性,使晶界处的硅质相收缩在三个晶粒交界处。对GDC薄膜的电导率测试研究表明,扩散掺杂Fe元素能够明显提高薄膜的电导率,在800℃退火条件下提高了数倍左右,晶体的电导激活能没有改变。当给薄膜掺杂Si元素后,测试其电导率并且与制备态和掺杂Fe元素的样品作对比,掺杂Si元素的样品电导率明显降低,而Fe元素的掺杂则可以明显提高其电导率,这进一步说明了掺杂Fe元素可以改变晶界处硅质相的润湿性,使晶界处的硅质相收缩在三个晶粒交界处,从而提高GDC薄膜的电导率。由于Ce02在还原气氛或者低氧分压条件下具有一定的电子电导,本论文通过研究氧分压与GDC薄膜电导率的关系,从实验方面验证了氧分压对GDC薄膜的电导率有一定的影响。通过控制不同的退火温度,本论文测试了在未退火(常温25 ℃)、500 ℃、800 ℃及1200 ℃退火温度下样品的晶粒尺寸以及微观形貌,通过研究它们的电学性能建立了晶粒尺寸大小与电导率的关系,从实验结果来看800 ℃是很合适的退火温度。
[Abstract]:Compared with the conventional oxygen ion conductor solid electrolyte Y doped stable Zr02 / YSZ / Gd doped ce 02N GDCs have been widely studied because of their high conductivity at medium temperature. In order to meet the development trend of electrolyte thin film and intermediate temperature, It is more and more important to study the preparation process and conductivity of GDC electrolyte. In this thesis, GDC thin films were prepared on single crystal A1203 substrate by reactive DC magnetron sputtering. The prepared GDC thin films have cubic fluorite structure, The results of preferential growth along the surface of GDC show that GDC thin films have typical columnar crystal structure. The results of TEM analysis showed that the grain size of GDC thin films varied from 10 nm to 100 nm at different annealing temperatures. The sol containing Fe and Si was prepared by sol-gel method, and the sol was coated on the surface of GDC films. Then Fe and Si elements are doped into grain boundaries by thermal diffusion process. The energy spectrum analysis of GDC films shows that there are silicon phases in the grain boundaries of GDC films, and the wettability of silicon phases at grain boundaries can be changed by doping Fe elements. The silicon phase at grain boundary shrinks at the junction of three grains. The conductivity measurement of GDC thin film shows that the diffusion doped Fe element can obviously improve the conductivity of the film, and it can be increased several times at 800 鈩，

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