Electronic, magnetic and thermoelectric properties of Nb-substituted Fe2TiO5 pseudobrookite compound: Ab initio study

摘要

Abstract Fe2TiO5, pseudobrookite, with a high Seebeck coefficient and very low thermal conductivity, shows promising thermoelectric properties. However, due to its low electrical conductivity, the ZT value of Fe2TiO5 is still very low. In this article, we report the effect of the Nb substitute on the crystal structure, electronic, magnetic and thermoelectric properties of Fe2TiO5 by employing first-principle calculations. The calculated electronic structures in GGA?+?U show that introducing Nb improves the electrical conductivity of the Fe2TiO5 and with the increasing Nb atoms content, the size of the band gap decreases. Our spin-polarized calculations reveal that Fe2?xNbxTiO5 components with X?=?0.125 and 0.375 have an absolute magnetization, while Fe2TiO5 shows anti-ferromagnetism behavior. As the amount of Nb in the Fe2TiO5 composition increases, the Seebeck coefficient increases. Also, in all samples, with increasing temperature, the Seebeck coefficient decreases. These results show that thermoelectric properties are improved by adding Nb to the compounds.