Transport properties and conduction mechanisms in CuFe2O4 and Cu1−xZnxGa0.3Fe1.7O4 compounds

Single-phase structure of CuFe2O4 and Cu1−xZnxGa0.3Fe1.7O4; with (0.0≤x≤0.5) are synthesized. Electrical conductivity measurements as a function of temperature are carried out in the frequency range (102–105 Hz) for the prepared samples. The obtained results of these materials reveal a metallic-like behavior in the low range of frequency. At high frequency regime metallic-to-semiconductor transition has been observed as the compositional parameter x increases. Metallic-like behavior is accompanied with samples having low Zn content, where cation–cation [Cu–Cu] interaction is major at the octahedral B-sites and semiconductor behavior is associated with compounds having high Zn content, where cation–anion–cation [Fe–O–Fe] interaction is most predominant at B-sites in these spinel oxides. All studied compositions exhibit a transition with change in the slope of conductivity versus temperature curve. This transition temperature is found to decrease linearly with increasing Zn concentration x. The relation of the universal exponent s with temperature indicates the presence of two hopping conduction mechanisms; the correlated barrier hopping CBH at low Zn content x≤0.2 and small polaron (SP) at Zn content x≥0.3.