PUB-2015-ETF

Enhanced Thermoelectric Figure of Merit in Thermally Robust, Nanostructured Superlattices based on SrTiO3

​Anas I. Abutaha , S.R. Sarath Kumar , Kun Li , Arash M. Dehkordi , Terry M. Tritt , and Husam N. Alshareef, "Enhanced Thermoelectric Figure of Merit in Thermally Robust, Nanostructured Superlattices based on SrTiO3"
​Chem. Mater., DOI: 10.1021/acs.chemmater.5b00144​
Anas I. Abutaha, S.R. Sarath Kumar, Kun Li, Arash M. Dehkordi, Terry M. Tritt, and Husam N. Alshareef
Superlattices, SrTiO3
2015
Thermoelectric (TE) metal oxides overcome crucial disadvantages of traditional heavy-metal-alloy based TE materials, such as toxicity, scarcity, and instability at high temperatures. Here, we report the TE properties of metal oxide superlattices, composed from alternative layers of 5% Pr3+ doped SrTiO3-δ (SPTO) and 20% Nb5+ doped SrTiO3-δ (STNO) fabricated using pulsed laser deposition (PLD). Excellent stability is established for these superlattices by maintaining the crystal structure and reproducing the TE properties after long-time (20 hours) annealing at high temperature (~1000 K). The introduction of oxygen vacancies as well as extrinsic dopants (Pr3+ and Nb5+), with different masses and ionic radii, at different lattice sites in SPTO and STNO layers, respectively, results in a substantial reduction of thermal conductivity via scattering a wider range of phonon spectrum without limiting the electrical transport and thermopower, and hence leading to an enhancement in the figure of merit (ZT). The superlattice composed of 20 SPTO/STNO pairs, 8 unit cells of each layer, exhibits a ZT of 0.46 at 1000 K, highest among SrTiO3-based thermoelectrics.