Ab initio investigation of the role of vanadium impurity states in SrTiO3 for thermoelectricity

Abstract

Despite their low cost, non-toxicity, thermal/chemical stability and relative abundance, oxides are not considered as promising materials for future thermoelectric devices. The main reason behind this lack of interest is their relatively high thermal conductivity. However, some oxides, such as n doped bulk SrTiO 3 exhibit a rather good power factor. Keeping in mind that alloying and nanostructuring are two efficient procedures to suppress the thermal conductivity, it is worth exploring pathways towards an enhancement of the thermopower. Here, we report that vanadium doping of SrTiO 3 gives rise to well defined resonant states allowing power factor of both n and p type over a relatively broad range of carrier concentrations. We investigate both the effects of a rigid band shift of the Fermi level and of realistic co-doping using DFT calculations.

Tuning the magnetic and electronic properties of strontium titanate by carbon doping

“…Codoping with La and Rh leads to the formation of clean band structures rather than mid-gap states [8]. Doping approaches mainly include (i) anion doping [5,21], (ii) cation doping [14,22,23], (iii) cation-anion codoping [13,[24][25][26], (iv) anion-anion codoping [27], and (v) cation-cation codoping [5,28]. In particular, the anion dopant of carbon (C) to replace oxygen has attracted much attention and is considered one of the appropriate anion alloy elements to introduce acceptor levels above the VBM of SrTiO3 because its size is closer to the size of the substituted host oxygen atoms, which is favorable for effective incorporation.…”