Finite size effect of proton-conductivity of amorphous silicate thin films based on mesoscopic fluctuation of glass network.
Finite size effect of proton-conductivity of amorphous silicate thin films based on mesoscopic fluctuation of glass network.
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基于玻璃网络介观涨落的非晶硅酸盐薄膜质子电导率有限尺寸效应
DOI：
10.1021/ja1091886
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发表时间：
2011
影响因子：
15
通讯作者：
S. Yamaguchi
中科院分区：
文献类型：
--
作者：
Y. Aoki;H. Habazaki;S. Nagata;A. Nakao;T. Kunitake;S. Yamaguchi
研究了非晶硅酸盐薄膜a-M（0.1）Si（0.9）O（x）（M = Al，Ga，Hf，Ti，Ta，La）质子导电性的有限尺寸效应。通过在10-1000 nm范围内改变厚度，在干燥空气中测量跨膜的质子传导率σ。M = Al、Ga和Ta的膜的σ通过将厚度减小到小于几百纳米而以幂律升高，并且增量在几十纳米的厚度处饱和。另一方面，M = Hf、Ti和La的膜的σ在>10 nm的范围内与厚度的减小无关。前者的电导率随厚度的变化可以用一个电阻网络模型来模拟，该模型包括两种电阻R（1）和R（2）（R（1）> R（2））以简单的π型点阵的形式随机分布的阵列。高分辨透射电子显微镜（TEM）表明，a-M（0.1）Si（0.9）O（x）薄膜是由凝聚畴和周围的非凝聚基体组成的异质微结构，这是由于纳米尺度上玻璃网络的涨落造成的。凝聚域具有蠕虫状形状，平均长度为几十纳米，并执行质子传导路径穿透不良传导基质的作用。得出的结论是，厚度依赖的电导率可以等同于在纳米范围内的互联域的分解网络的有限尺寸标度。
The finite size effect of proton conductivity of amorphous silicate thin films, a-M(0.1)Si(0.9)O(x) (M = Al, Ga, Hf, Ti, Ta, and La), was investigated. The proton conductivity across films, σ, was measured in dry air by changing the thickness in the range of 10-1000 nm. σ of the films with M = Al, Ga, and Ta was elevated in a power law by decreasing thickness into less than a few hundred nanometers, and the increment was saturated at a thickness of several 10's of nanometers. On the other hand, σ of the films with M = Hf, Ti, and La was not related to the decrease of the thickness in the range of >10 nm. Thickness-dependent conductivity of the former could be numerically simulated by a percolative resistor network model that involves the randomly distributed array of two kinds of resistors R(1) and R(2) (R(1) > R(2)) in the form of a simple cubic-type lattice. High-resolution TEM clarified that a-M(0.1)Si(0.9)O(x) films involved heterogeneous microstructures made of the condensed domain and the surrounding uncondensed matrix due to the fluctuation of glass networks on the nanometer scale. The condensed domain had a wormlike shape with an average length of several 10's of nanometers and performed the role of the proton conduction pathway penetrating through the poorly conducting matrix. It was concluded that the thickness-dependent conductivity could be identical to finite-size scaling of the percolative network of the interconnected domains in the nanometer range.