METAL-CLUSTERS AND MODEL ROCKS - ELECTROMAGNETIC PROPERTIES OF CONDUCTING FRACTAL AGGREGATES

被引:50
作者
ZABEL, IHH
STROUD, D
机构
[1] Department of Physics, Ohio State University, Columbus
来源
PHYSICAL REVIEW B | 1992年 / 46卷 / 13期
关键词
D O I
10.1103/PhysRevB.46.8132
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
We present a numerical study of fractal metallic aggregates embedded in a two-dimensional (2D) dielectric host. The metallic clusters are constructed from Drude-like bonds, while the dielectric host is taken to have purely capacitive response. The clusters are either grown randomly [by diffusion-limited aggregation (DLA)] or by a deterministic algorithm which generates self-similar clusters. The effective ac response of the composite is computed using the Y-DELTA algorithm of Frank and Lobb. For finite clusters, either random or deterministic, the far-infrared absorption per unit mass of metal is found to be greatly increased over that of isolated metallic particles. This provides a possible explanation of the enhancement observed in suspensions of small metal particles, assuming a fractal clustering is present. At higher frequencies, the random fractals lead to a broad surface-plasmon absorption spectrum, while the ordered fractals have an optical conductivity which appears to be self-similar in frequency. When a random 2D DLA cluster is allowed to percolate across the composite, we find a strong low-frequency enhancement of the dielectric constant, similar to the enhancement observed in brine-saturated porous rocks. We discuss the possible relevance of the model, and its probable limitations, as applied to real composites.
引用
收藏
页码:8132 / 8138
页数:7
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