RT Journal Article
T1 Thermal evolution of structures and conductivity of Pr-substituted BaZr0.7Ce0.2Y0.1O3-delta: potential cathode components for protonic ceramic fuel cells
A1 Heras Juaristi, Gemma
A1 Amador, Ulises
A1 Fuentes, Rodolfo
A1 Chinelatto, Adilson
A1 Romero de Paz, Julio
A1 Ritter, Clemens
A1 Fagg, Duncan
A1 Pérez Coll, Domingo
A1 Mather, Glenn
AB 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.
PB Royal Society of Chemitry
SN 2050-7488
YR 2017
FD 2017
LK https://hdl.handle.net/20.500.14352/100226
UL https://hdl.handle.net/20.500.14352/100226
LA eng
NO 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.
NO 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.
NO Ministerio de Economía y Competitividad (España)
NO Ministry of Education (Brazil)
NO Fundação para a Ciência e a Tecnología (Portugal)
NO Center for Research in Energy and Materials (Brazil)
DS Docta Complutense
RD 21 abr 2025