Thermoelectric performance of Nb-doped SrTiO3 enhanced by reduced graphene oxide and Sr deficiency cooperation

authors	Okhay, O; Zlotnik, S; Xie, WJ; Orlinski, K; Gallo, MJH; Otero-Irurueta, G; Fernandes, AJS; Pawlak, DA; Weidenkaff, A; Tkach, A
nationality	International
journal	CARBON
keywords	DIELECTRIC PERMITTIVITY; POWER; CERAMICS; TEMPERATURE; TRANSPORT; VACANCIES; FIGURE; CARBON
abstract	Oxide materials are of current interest as high-temperature thermoelectrics in the automotive and manufacturing energy-harvesting sectors due to high chemical robustness, low toxicity and low cost. Driven by a need to improve the thermoelectric performance of n-type oxides to the level of p-type analogues, ceramics and composites based on donor-doped SrTiO3 are considered as a promising material. Here Nb-doped SrTiO3 with Nb content of 10 and 15% as well as Sr/(Nb + Ti) ratio of 1.00 and 0.98 was mixed with 0.6 wt. % of graphene oxide (GO) prepared by Hummer-based method and conventionally sintered in atmosphere of H-2/N-2 to reduce both Nb-doped SrTiO3 and GO. Addition of reduced GO in combination with introduction of Sr vacancies provides a synergistic effect of fastening charge transport and thereby increasing electrical conductivity sigma and suppressing the thermal conductivity kappa. These factors, together with a moderate Seebeck coefficient S, result in a high power factor PF = S-2 x sigma up to similar to 1.98 mW/(K(2)m) and thermoelectric figure of merit ZT = PF x T/kappa up to 0.29. These findings offer further prospects for seeking high performance SrTiO3-based thermoelectrics by modification with reduced GO. (C) 2018 Elsevier Ltd. All rights reserved.
publisher	PERGAMON-ELSEVIER SCIENCE LTD
issn	0008-6223
isbn	1873-3891
year published	2019
volume	143
beginning page	215
ending page	222
digital object identifier (doi)	10.1016/j.carbon.2018.11.023
web of science category	Chemistry, Physical; Materials Science, Multidisciplinary
subject category	Chemistry; Materials Science
unique article identifier	WOS:000456710500024