Doped ceramics of indium oxides for negative permittivity materials in MHz-kHz frequency regions

Negative permittivity has been widely studied in various metamaterials and percolating composites, of which the anomalous dielectric behavior was attributed to critical structural properties of building blocks. Herein, mono-phase ceramics of indium tin oxides (ITO) were sintered for epsilon-negative materials in MHz-kHz frequency regions. Electrical conductivity and complex permittivity were analyzed with Drude-Lorentz oscillator model. Carriers' characters were measured based on Hall effect and the magnitude and frequency dispersion of negative permittivity were mainly determined by carrier concentration. Temperature-dependent dielectric properties further proved the epsilon-negative behaviors were closely associated with free carriers' collective responses. It's found that negative permittivity of ITO ceramics was mainly caused by plasma oscillations of free carriers, while the dielectric loss was mainly attributed to conduction loss. Negative permittivity realized here was related to materials intrinsic nature and this work preliminarily determined the mechanism of negative permittivity in doped ceramics from the perspective of carriers. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

The study investigated the negative permittivity in indium tin oxide (ITO) ceramics, revealing that the negative permittivity is mainly caused by plasma oscillations of free carriers, while the dielectric loss is mainly attributed to conduction loss. The magnitude and frequency dispersion of negative permittivity are mainly determined by carrier concentration, and the mechanism has been preliminarily understood from the perspective of carriers.