Further insights into thermoelectric properties of nonstoichiometric titanium oxide fabricated by high pressure and high temperature

The present work explores the feasibility of advancing the thermoelectric properties of nonstoichiometric TiO_2?x through introducing more and more oxygen deficiencies. Compared with previous work, it is found that this compositional manipulation induces phase transition; in addition, the scattering mechanisms of both carrier and phonon have changed, resulting in the temperature-independent electrical resistivity, inferior electrical performance and an unexpected high thermal conductivity. As a consequence, a moderate zT value of 0.13 is obtained in TiO_1.72 at 600?℃. Through this work, we understand deeply about thermoelectric properties of nonstoichiometric titanium oxide by high pressure and high temperature, and further investigations about this system have been directed.