High performance (ZT>1) n-type oxide thermoelectric composites from earth abundant materials. (June 2021)

• Record Type: Journal Article
• Authors: Acharya, Megha; Jana, Subhra Sourav; Ranjan, Mani; Maiti, Tanmoy
• Is Part Of: Nano energy. Volume 84(2021)
• Publication Date: 2021-06
• Subjects: Thermoelectrics -- Oxide -- Perovskite -- Composite -- Rare-earth-free; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2021.105905
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Oxide-based thermoelectric materials have the advantages of high-temperature stability, low toxicity and low processing cost comparted to other metal-based systems. However, achieving ZT > 1 remain elusive especially for n-type bulk oxide thermoelectrics. Here, we report the experimental demonstration of ZT > 1 in n-type oxides by synthesizing composites of Nb-doped SrTiO3 (STN) with natural graphite. Introduction of conductive graphite inclusions in STN matrix has led to a surge in electrical conductivity due to 21-times increase in weighted mobility ( μ w ) of electrons resulting in high thermoelectric power factor ~5400 µW m K 2, which is ~16-times higher than that of pure STN. Furthermore, we could restrain the increase in thermal conductivity by attaining enhanced Umklapp scattering along with phonon-glass-like temperature-independent phonon mean-free-path above Debye temperature. We have achieved the maximum ZT ~1.42 in STN+ 0.5 wt% G composite, which is 15-times enhancement compared to STN. Our proposed way of designing rare-earth-free composites with graphite can potentially open up the possibility of fabricating novel high-temperature thermoelectric generators. Graphical Abstract: ga1 Highlights: Synthesized composite with graphite to enhance ZT of SrTi0.85 Nb0.15 O3 by 15 times. Achieved record high ZT ~ 1.42 in rare-earth free bulk n-type oxide thermoelectrics. Oxide composites have shown ZT> 1.2 in the broad temperature range, 850–1050 K. Attained high TE power factor ~ 5400 µW m K 2, ~16 times higher than that of STN.