Proton conductivity of columnar ceria thin-films grown by chemical vapor deposition
Proton conductivity of columnar ceria thin-films grown by chemical vapor deposition
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DOI：
10.1039/c2cp43036c
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发表时间：
2013-01-01
影响因子：
3.3
通讯作者：
Haile, Sossina M.
中科院分区：
文献类型：
--
作者：
Oh, Tae-Sik;Boyd, David A.;Haile, Sossina M.
采用金属有机化学气相沉积法制备了未掺杂的氧化铈柱状薄膜。该薄膜沉积在pt涂层的MgO（100）衬底上，显示出纳米级晶粒尺寸的柱状微观结构，总孔隙率接近30%。用交流阻抗谱法测定了通过平面（厚度模式）的电导率。质子传导是在350-400摄氏度以下观察到的，其大小取决于气相水蒸气压力。总体行为表明质子沿暴露的晶面和平行晶界发生输运。没有观察到由于与输运方向垂直的晶界引起的阻抗。在200-400℃的温度范围内，质子电导率大约是纳米颗粒的四倍，这与CVD膜中沿排列的晶粒表面的输运增强一致。
Columnar thin films of undoped ceria were grown by metal-organic chemical vapor deposition. The films, deposited on Pt-coated MgO(100) substrates, display a columnar microstructure with nanometer scale grain size and similar to 30% overall porosity. Through-plane (thickness mode) electrical conductivity was measured by AC impedance spectroscopy. Proton conduction is observed below 350-400 degrees C, with a magnitude that depends on gas-phase water vapor pressure. The overall behavior suggests proton transport that occurs along exposed grain surfaces and parallel grain boundaries. No impedance due to grain boundaries normal to the direction of transport is observed. The proton conductivity in the temperature range of 200-400 degrees C is approximately four times greater than that of nanograined bulk ceria, consistent with enhanced transport along aligned grain surfaces in the CVD films.