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Phonon−glass and heterogeneous electrical transport in a‑site-deficient SrTiO3

hal.structure.identifierInstitute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery
dc.contributor.authorPOPURI, Srinivasa Rao
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorDECOURT, Rodolphe
hal.structure.identifierEaStCHEM School of Chemistry
dc.contributor.authorMCNULTY, Jason
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorPOLLET, Michaël
hal.structure.identifierISIS Facility
dc.contributor.authorFORTES, Dominic
hal.structure.identifierEaStCHEM School of Chemistry
dc.contributor.authorMORRISON, Finlay D.
hal.structure.identifierDepartment of Chemistry
dc.contributor.authorSENN, Mark
hal.structure.identifierInstitute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery
dc.contributor.authorBOS, Jan-Willem G.
dc.date.issued2019
dc.identifier.issn1932-7447
dc.description.abstractEnThe phonon–glass electron crystal concept is one of the key guiding principles for the development of efficient thermoelectric materials. Here, we confirm that SrTiO3 becomes a phonon–glass for large numbers of A-site vacancies in the Sr1–xLa0.67x□0.33xTiO3 series and show that its electron crystal properties are stymied by the presence of a core–shell grain structure. Thermal conductivity, heat capacity, and neutron powder diffraction, complemented by representational analysis and phonon calculations, were used to investigate the thermal transport. This reveals that the heat carrying modes are dominated by Sr motions and that these become more localized upon the introduction of the A-site vacancies, consistent with the observed phonon–glass state. Impedance spectroscopy and direct current electrical measurements were used to probe the electrical properties of insulating and conducting samples. This reveals the coring of grains due to oxidation on cooling from sintering temperatures. The resultant insulating shell limits the thermoelectric power factor to S2/ρ = 0.45 mW m–1 K–2 and the figure-of merit to ZT = 0.15 at 900 K for Sr0.20La0.53□0.27Ti0.95Nb0.05O3−δ. The thermal properties of these materials are, therefore, controlled by an intrinsic feature of the microstructure (i.e., the A-site vacancies), whereas the electrical properties are grain boundary limited, which in principle can be controlled independently to raise S2/ρ and ZT.
dc.language.isoen
dc.publisherAmerican Chemical Society
dc.title.enPhonon−glass and heterogeneous electrical transport in a‑site-deficient SrTiO3
dc.typeArticle de revue
dc.identifier.doi10.1021/acs.jpcc.8b10520
dc.subject.halChimie/Matériaux
bordeaux.journalJournal of Physical Chemistry C
bordeaux.page5198-5208
bordeaux.volume123
bordeaux.issue9
bordeaux.peerReviewedoui
hal.identifierhal-02066754
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-02066754v1
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