2026-08-22T00:38:41Zhttps://docta.ucm.es/rest/oai/request

oai:docta.ucm.es:20.500.14352/1002262024-12-14T00:46:24Zcom_20.500.14352_14col_20.500.14352_15

Thermal evolution of structures and conductivity of Pr-substituted BaZr0.7Ce0.2Y0.1O3-delta: potential cathode components for protonic ceramic fuel cells Heras Juaristi, Gemma Amador, Ulises Fuentes, Rodolfo Chinelatto, Adilson Romero de Paz, Julio Ritter, Clemens Fagg, Duncan Pérez Coll, Domingo Mather, Glenn 546 Química inorgánica (Química) 2303.26 Estructura de Los Compuestos Inorgánicos 2303.24 Tierras Raras 2211.26 Dispositivos de Estado Sólido The authors would like to congratulate Professor Tony West on the occasion of his 70th birthday. GCM especially appreciates the invaluable guidance in solid-state chemistry provided to him by Prof. West. This work was supported by the MINECO, Spain (ENE2015-66183-R, MAT2016-78362-C4-1-R), CSIC, Spain (i-link0743), CAPES, Brazil (PVE, Proceso 88881.03418/2013-1) and the FCT, Portugal (POPH, PTDC CTM-EME 6319 2014). Access to the neutron facilities at the Institut Laue Langevin (Grenoble, France) and the National Synchrotron Light Laboratory (LNLS, Campinas, Brazil) under grant 5-24-55(D2B) and research proposal D10B-XRD1-16166, respectively, is gratefully acknowledged. U. A. also thanks the Universidad San Pablo for financial support. A complete solid solution forms between the perovskite proton conductor BaZr0.7Ce0.2Y0.1O3 d (BZCY72) and BaPr0.9Y0.1O3-d (BPY) on synthesis by the Pechini method and high-temperature annealing. Phase fields of selected members of the Ba(Zr0.7Ce0.2)1-(x/0.9)PrxY0.1O3-d series were studied as a function of composition and temperature by high-resolution neutron powder diffraction revealing symmetry changes in the sequence Pnma / Imma / R3c / Pm-3m. Higher symmetry is favoured for low Pr contents and high temperatures, as consideration of tolerance factor suggests. A volume contraction, ascribed to dehydration, is observed by synchrotron X-ray diffraction on heating in air for lower x. Magnetic measurements and structural data support the presence of Pr in the IV valence state on the perovskite B site. Thermogravimetric analysis in CO2 to near 1253 K indicates better chemical stability for x <= 0.445, whereas decomposition occurred for higher x. Electrical conductivity increases by over two orders of magnitude in dry air at lower temperature from x = 0.225 to 0.675; total conductivity reaches a value of 0.4 S cm-1 at 1173 K for x = 0.675. The series exhibits electron–hole transport with a positive pO2 dependence which increases with temperature, consistent with participation of oxygen vacancies in charge compensation of the Y3+ acceptor dopant. The activation energy for thermally activated hole hopping in air in the range 523–773 K decreases from near 1 eV for BZCY72 to near 0.4 eV for x = 0.675. Conductivity is generally lower in humidified N2 and air (pH2O = 0.023 atm) than the corresponding dry atmospheres, consistent with consumption of holes by less mobile protonic species; however for x <= 0.225 the lower concentration of electron holes concomitant with higher oxygen-vacancy content in N2 results in slightly higher conductivity in wet conditions due to hydration of vacancies. Ministerio de Economía y Competitividad (España) Ministry of Education (Brazil) Fundação para a Ciência e a Tecnología (Portugal) Center for Research in Energy and Materials (Brazil) Depto. de Química Inorgánica Fac. de Ciencias Químicas TRUE pub 2024-02-08T09:18:23Z 2024-02-08T09:18:23Z 2017 journal article https://hdl.handle.net/20.500.14352/100226 2050-7488 10.1039/c7ta09570h 2050-7496 eng MAT2016-78362-C4-1-R info:eu-repo/grantAgreement/MINECO//ENE2015-66183-R/ES/CELDAS ELECTROQUIMICAS CERAMICAS ESTABILIZADAS CON HALUROS PARA UNA CONVERSION Y PRODUCCION OPTIMIZADA DE HIDROGENO/ D10B-XRD1-16166 5-24-55(D2B) Heras-Juaristi, G., Amador, U., Fuentes, R. O., Chinelatto, A. L., de Paz, J. R., Ritter, C., ... & Mather, G. C. (2018). Thermal evolution of structures and conductivity of Pr-substituted BaZr 0.7 Ce 0.2 Y 0.1 O 3− δ: potential cathode components for protonic ceramic fuel cells. Journal of Materials Chemistry A, 6(13), 5324-5334. Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ metadata only access application/pdf Royal Society of Chemitry