Tunable negative permittivity of Bi2O3–SiO2/MWCNT glass-nanocomposites at radio frequency region

Abstract

In this work, the negative dielectric constant in the frequency range 1 MHz to 3 GHz and the temperature range 140 K to 300 K are studied. The dielectric parameters (e′, e″, tanδ), conductivity ( $${\sigma }_{\text{ac}}$$ ), reactance (Z′, Z″), and magnetization (Ms) with respect to the multiwall carbon nanotube (MWCNT) loading are discussed in detail. A percolation phenomenon in ac conductivity ( $${\sigma }_{\text{ac}}$$ ) is noticed when the MWCNT content increased from 5 to 10 wt%. The perceived ac conductivity spectra of various trends of present BS/MWCNT glass-nanocomposites are explained by Jonscher’s power law or Drude model. The negative permittivity is observed with the formation of the 3D conductive network, and negative value and frequency range of the real part of permittivity (e′) are precisely adjusted by varying concentration of MWCNT. The resonance frequency-dependent negative permittivity behaviour in the BS/MWCNT glass-nanocomposite with low content MWCNT can be explained by Lorentz model, and the plasma-like negative permittivity behaviour was explained by Drude model. This work offers a favourable outcome to tunable negative dielectric behaviour and high dielectric constant materials.