Temperature-dependent dielectric permittivity in Mott variable-range hopping

Determine how the temperature dependence of the effective dielectric permittivity in carbon-contaminated spark-plasma-sintered BaTiO₃ ceramics affects the temperature dependence of resistivity and the Mott variable-range hopping parameter T₀, including the associated dependence of the localized-state density N(E) and carrier localization radius.

Background

The paper investigates carbon-contaminated spark-plasma-sintered BaTiO₃ ceramics whose low-temperature electrical conduction follows the Mott variable-range hopping law. The hopping parameter T₀ depends on the density of localized electronic states and the carrier localization radius, while the localization radius is itself related to the effective dielectric permittivity.

The authors observe that the effective dielectric permittivity varies substantially with temperature and argue that this variation should influence the hopping parameters. However, the screening of nanoparticle depolarization fields, local band bending, spontaneous polarization, and the density of localized states are mutually coupled, so the quantitative effect of the dielectric-permittivity variation on resistivity remains unresolved.