Electrical properties of Si⁴⁺ substituted copper ferrite

Abstract

The electrical resistivity, ϱ, and Seebeck coefficient, α, for the system Cu_1+xSi_xFe_2−2xO₄ (where x = 0.05, 0.1, 0.15, 0.2 and 0.3) have been studied as a function of temperature. Temperature variation of the resistivity exhibits two breaks. Each break is associated with a change in activation energy. The conduction process at low temperature is governed by the reaction Cu ¹⁺_A + Cu ²⁺_A →Cu ²⁺_A + Cu ¹⁺_A . However, at higher temperature, it is due to intersite cation exchange and reoxidation such as Cu ²⁺_A + Fe ³⁺_B → Cu ²⁺_B + Fe ³⁺_A . Measurement of the Seebeck coefficient, α, from room temperature to 800 K reveals n-type conduction for the sample with x= 0.05, while the measurements for other samples show p-type conduction for lower temperatures and n-type conduction at higher temperatures. The activation energies in the paramagnetic region are found to be less than those in the ferrimagnetic region.