Structure–conductivity relations of simulated highly porous nanoparticle aggregate films
Structure–conductivity relations of simulated highly porous nanoparticle aggregate films
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模拟高多孔纳米颗粒聚集体薄膜的结构-电导率关系
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
L. Mädler
中科院分区：
文献类型：
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作者：
N. Riefler;L. Mädler
由纳米颗粒聚集体组成的多孔膜的导电性从理论上评价了聚集体结构和薄膜堆积密度。聚集体是由5-30个直径为10 nm的初级颗粒组成的分形。在0.5 ~ 1 μm范围内的模拟盒中得到了膜的性能。研究了填料密度为0.01 ~ 0.15时薄膜的电导率。所有使用纳米粒子聚集体的气溶胶沉积技术制备的薄膜都表现出平行于聚集体移动方向的平面之间的渗透行为。他们还遵循经典的电导率渗透关系，而临界渗透堆积密度取决于用于构建薄膜的骨料尺寸和结构。使用较大聚集体作为构建块的薄膜比接近渗透极限的较小聚集体具有更高的电导率。为了验证和补充信息，开发了两个独立的模型：一个模型遵循渗透理论以获得详细的物理见解，另一个模型计算精确的电导率，但代价是一些细节。这一分析为这些薄膜的传导骨干结构提供了新的见解，涉及聚集体内部的颈部接触和聚集体之间的晶界接触。所显示的结果对于这些薄膜的太阳能应用非常重要，特别是对于高灵敏度通常被低导电性抵消的气体传感器。
Electrical conductivity of porous films composed of nanoparticle aggregates is theoretically evaluated with respect to aggregate structure and film packing density. The aggregates are fractals composed of 5–30 primary particles with diameter of 10 nm. The film properties are derived from simulated boxes in the range of 0.5–1 μm. The electrical conductivity across the films of packing densities ranging from 0.01 to 0.15 was studied. All films prepared by an aerosol deposition technique, which uses nanoparticle aggregates, exhibited percolation behavior between planes parallel to the moving direction of the aggregates. They also followed the classical percolation relation for electrical conductivity while the critical percolation packing density depends on the aggregate size and structure used to build the films. Films using larger aggregates as building blocks have higher electrical conductance than smaller aggregates close to the percolation limit. For validation and supplementary information, two independent models are developed: one model follows the percolation theory to get detailed physical insights and another one computes the exact conductivities but at the cost of some details. This analysis gives new insights into the conduction backbone structures of these films with regard to neck contacts within an aggregate and grain boundary contacts between aggregates. The results shown are important for solar application of these films and especially for gas sensors where high sensitivity is often counteracted by low conductivity.