Effect of A-Site Cation Deficiency on the Thermoelectric Performance of Donor-Substituted Strontium Titanate

authors	Kovalevsky, AV; Yaremchenko, AA; Populoh, S; Weidenkaff, A; Frade, JR
nationality	International
journal	JOURNAL OF PHYSICAL CHEMISTRY C
keywords	NB-DOPED SRTIO3; TRANSPORT-PROPERTIES; CERAMICS; OXIDES; CONDUCTIVITY; TEMPERATURE; BEHAVIOR; SENSORS; PHASES; DEFECT
abstract	Donor-substituted strontium titanate is known as one of the best highly performing n-type oxide thermoelectrics. In the present work, structural, microstructural, and thermoelectric properties of Sr1-xPrxTiO3 +/-delta, Sr1-1.5x PrxTiO3 +/-delta, and Sr1-yTi0.8Nb0.2O3 +/-delta (x = 0.05-0.30, y = 0-0.10) perovskite-type titanates were assessed to identify the impact of nominal A-site deficiency on thermoelectric performance. A large increase in power factor was observed for A-site nonstoichiometric materials at high donor-substitution level, provided by the favorable changes in electronic structure, defect chemistry, and microstructure. Complex dependence of the total conductivity and Seebeck coefficient on strontium deficiency suggests effects of microstructure on the electrical properties of Pr-and Nb-substituted ceramic samples. Formation of oxygen vacancies was found to suppress lattice thermal conductivity at low and intermediate temperatures, whereas the electronic part of the heat transfer increases for cation-deficient materials. For both Pr- and Nb-substituted titanates, introducing nominal A-site deficiency represents a promising strategy for improving performance.
publisher	AMER CHEMICAL SOC
issn	1932-7447
year published	2014
volume	118
issue	9
beginning page	4596
ending page	4606
digital object identifier (doi)	10.1021/jp409872e
web of science category	Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary
subject category	Chemistry; Science & Technology - Other Topics; Materials Science
unique article identifier	WOS:000332756000004