Anomalous Efros–Shklovskii variable range hopping conduction in composites of polymer and iron carbide nanoparticles embedded in carbon

Efros–Shklovskii variable range hopping (ES-VRH) conduction mechanism [ρ=ρ0exp(TES/T)1/2][ρ=ρ0exp(TES/T)1/2] is observed in composites of polymer and iron carbide nanoparticles embedded in carbon relatively at high temperatures. A crossover from one ES-VRH type to another ES-VRH type is observed with different ES temperature (TESTES) and prefactor (ρ0ρ0) as temperature decreases.