000110585 001__ 110585
000110585 005__ 20251219150009.0
000110585 0247_ $$2doi$$a10.3390/sym13050782
000110585 0248_ $$2sideral$$a127289
000110585 037__ $$aART-2021-127289
000110585 041__ $$aeng
000110585 100__ $$aConstantinescu G.
000110585 245__ $$aExploring the high-temperature electrical performance of Ca3-xLaxCo4O9 thermoelectric ceramics for moderate and low substitution levels
000110585 260__ $$c2021
000110585 5060_ $$aAccess copy available to the general public$$fUnrestricted
000110585 5203_ $$aAliovalent substitutions in Ca3Co4O9 often result in complex effects on the electrical properties and the solubility, and impact of the substituting cation also depends largely on the preparation and processing method. It is also well-known that the monoclinic symmetry of this material’s composite crystal structure allows for a significant hole transfer from the rock salt-type Ca2CoO3 buffer layers to the hexagonal CoO2 ones, increasing the concentration of holes and breaking the electron-hole symmetry from the latter layers. This work explored the relevant effects of relatively low La-for-Ca substitutions, for samples prepared and processed through a conventional ceramic route, chosen for its simplicity. The obtained results show that the actual substitution level does not exceed 0.03 (x < 0.03) in Ca3-xLaxCo4O9 samples with x = 0.01, 0.03, 0.05 and 0.07 and that further introduction of lanthanum results in simultaneous Ca3Co4O9 phase decomposition and secondary Ca3Co2O6 and (La, Ca)CoO3 phase formation. The microstructural effects promoted by this phase evolution have a moderate influence on the electronic transport. The electrical measurements and determined average oxidation state of cobalt at room temperature suggest that the present La substitutions might only have a minor effect on the concentration of charge carriers and/or their mobility. The electrical resistivity values of the Ca3-xLaxCo4O9 samples with x = 0.01, 0.03 and 0.05 were found to be ~1.3 times (or 24%) lower (considering mean values) than those measured for the pristine Ca3Co4O9 samples, while the changes in Seebeck coefficient values were only moderate. The highest power factor value calculated for Ca2.99La0.01Co4O9 (~0.28 mW/K2m at 800 °C) is among the best found in the literature for similar materials. The obtained results suggest that low rare-earth substitutions in the rock salt-type layers can be a promising pathway in designing and improving these p-type thermoelectric oxides, provided by the strong interplay between the mobility of charge carriers and their concentration, capable of breaking the electron-hole symmetry from the conductive layers. © 2021 by the authors.
000110585 536__ $$9info:eu-repo/grantAgreement/ES/DGA/T54-20R$$9info:eu-repo/grantAgreement/ES/FEDER/POCI-01-0145-031875$$9info:eu-repo/grantAgreement/ES/MINECO-FEDER/MAT2017-82183-C3-1-R
000110585 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttps://creativecommons.org/licenses/by/4.0/deed.es
000110585 590__ $$a2.94$$b2021
000110585 592__ $$a0.54$$b2021
000110585 594__ $$a4.3$$b2021
000110585 591__ $$aMULTIDISCIPLINARY SCIENCES$$b34 / 74 = 0.459$$c2021$$dQ2$$eT2
000110585 593__ $$aChemistry (miscellaneous)$$c2021$$dQ2
000110585 593__ $$aPhysics and Astronomy (miscellaneous)$$c2021$$dQ2
000110585 593__ $$aComputer Science (miscellaneous)$$c2021$$dQ2
000110585 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion
000110585 700__ $$aRasekh S.
000110585 700__ $$aAmirkhizi P.
000110585 700__ $$aLopes D.V.
000110585 700__ $$aVieira M.A.
000110585 700__ $$aKovalevsky A.V.
000110585 700__ $$aDiez J.C.
000110585 700__ $$0(orcid)0000-0001-7056-0546$$aSotelo Mieg A.E.$$uUniversidad de Zaragoza
000110585 700__ $$0(orcid)0000-0002-0794-3998$$aMadre Sediles, M.A.$$uUniversidad de Zaragoza
000110585 700__ $$0(orcid)0000-0003-3995-5763$$aTorres Portero, M.A.$$uUniversidad de Zaragoza
000110585 7102_ $$15002$$2305$$aUniversidad de Zaragoza$$bDpto. Ingeniería Diseño Fabri.$$cÁrea Expresión Gráfica en Ing.
000110585 7102_ $$15001$$2065$$aUniversidad de Zaragoza$$bDpto. Ciencia Tecnol.Mater.Fl.$$cÁrea Cienc.Mater. Ingen.Metal.
000110585 773__ $$g13, 5 (2021), 782 [15 pp]$$pSymmetry (Basel)$$tSymmetry$$x2073-8994
000110585 8564_ $$s2677384$$uhttps://zaguan.unizar.es/record/110585/files/texto_completo.pdf$$yVersión publicada
000110585 8564_ $$s2761754$$uhttps://zaguan.unizar.es/record/110585/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada
000110585 909CO $$ooai:zaguan.unizar.es:110585$$particulos$$pdriver
000110585 951__ $$a2025-12-19-14:58:11
000110585 980__ $$aARTICLE