Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Optical properties of some metal-insulator composites

Thesis/Dissertation ·
OSTI ID:6814759
Ni-MgO granular composites were prepared by coprecipitation of NiO-MgO solid solutions and their preferential reduction in a hydrogen atmosphere. Measured reflection spectra of the composites were better described by the Effective Medium Approximation (EMA) than by the Maxwell-Garnett Theory (MGT). The conductivities and the dielectric constants were derived by a Kramers-Kronig transformation, and they showed a qualitative agreement with the EMA. In the far-infrared region, the percolation transition was observed in the reflection spectra, and also seen in the derived conductivities and the dielectric constants. The far-infrared absorption of Ag-smoke - teflon composites was studied. Because of the high resistivity of the oxide layer, the far-infrared electric dipole absorption was enhanced by three of four orders of magnitude, and it became comparable to the magnetic dipole absorption. The effects of the oxide coating on the infrared and visible absorption of silver smoke were also studied using Ag-smoke - KBr composites. In the infrared and visible region, the complete Mie theory gave better descriptions of the experimental results than the MGT. Comparison of the experimental data and the Mie calculation showed that the oxide coating on the particles did not strongly affect the extinction coefficient of the Ag-smoke - KBr composite in the near-infrared and visible range.
Research Organization:
Ohio State Univ., Columbus (USA)
OSTI ID:
6814759
Country of Publication:
United States
Language:
English