Temperature dependence of thermoelectric properties in V2 O5 thin film
Manil Kang, Sok Won Kim and Ji-Wook Ryu
In order to investigate the temperature dependence of thermophysical properties in crystalline V2 O5 thin film, we measure the Seebeck coefficient and the electrical conductivity, and examine the thermoelectric behavior of the film near the transition temperature (Tc). Based on X-ray diffraction (XRD) results, lattice distortion induced by oxygen vacancy formation is observed above 598 K, and the phase transformation develops at 773 K. The crystalline V2 O5 film reveals n-type conduction, and the decreasing trend in the Seebeck coefficient underwent a change above 513 K. The film’s resistivity and Seebeck coefficient exhibit an insulating or semiconducting state below 513 K, and these behaviors change above 513 K. The power factor (PF) changed significantly with a striking peak at 573 K. This result is due to the changes in resistivity and the Seebeck coefficient near Tc. Our results suggest that the metal-insulator transition (MIT) in V2 O5 film is not caused by phase transformation due to the excessive emission of oxygen. Based on our results, we suggest that the MIT in V2 O5 film occurs due to lattice distortion induced by the formation of vanadyl-oxygen vacancies.
Keywords: V2 O5, metal-to-insulator transition, thermoelectric properties, Seebeck coefficient, power factor, resistivity