Electric conductivity of a bulk composite based on Bi$_2$Te$_3$/SiO$_2$ core-shell nanoparticles

Composite Bi$_2$Te$_3$/SiO$_2$ nanoparticles of the core-shell type have been synthesized for the first time with a view to creating bulk composites possessing high thermoelectric figure of merit (conversion efficiency). It is suggested that bulk composited based on Bi$_2$Te$_3$/SiO$_2$ nanoparticles will provide a combination of low lattice heat conduction due to SiO$_2$ insulator and rather high electric conduction due to charge-carrier tunneling via dielectric spacers between adjacent Bi$_2$Te$_3$ semiconductor grains. The electric resistance of the composite increases with increasing temperature in the range of 130–300 K. This temperature dependence can be described in terms of a tunneling conduction model.