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Anomalous X‐ray diffraction study of Pr‐substituted BaCeO 3 − δ
Author(s) -
Basbus Juan F.,
Caneiro Alberto,
Suescun Leopoldo,
Lamas Diego G.,
Mogni Liliana V.
Publication year - 2015
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520615010203
Subject(s) - orthorhombic crystal system , crystallography , rietveld refinement , ionic bonding , crystal structure , doping , proton , absorption edge , electronic structure , materials science , powder diffraction , crystal (programming language) , chemistry , ion , analytical chemistry (journal) , band gap , physics , computational chemistry , optoelectronics , organic chemistry , chromatography , quantum mechanics , computer science , programming language
The effect of Pr doping on the crystal structure and site occupancy was studied for the nominally synthesized BaCe 1 − x Pr x O 3 − δ ( x = 0, 0.2, 0.4, 0.6 and 0.8) perovskites using anomalous X‐ray powder diffraction (AXRD) data and Rietveld analysis. Crystal structure parameters were accurately determined using 10 000 eV photons, and the Pr occupancy was refined using data collected with 5962 eV photons, close to the Pr L III absorption edge. BaCe 1 − x Pr x O 3 − δ crystallizes in the Pnma (No. 62) space group for all x values. Pr cations are mainly located at the Ce sites (perovskites B site), but a small fraction of them increasingly substitute some of the Ba ions at the A site as Pr content increases. The Pr doping introduces electronic defects (Pr +3 /Pr +4 ) and oxygen vacancies needed for H 2 O incorporation and H‐ionic conductivity. A decrease in the orthorhombic distortion would produce the opposite effects on the electronic and ionic mobility. The electronic mobility should increase due to an improvement in the overlap of the (Ce/Pr)4 f –O2 p orbital, while the proton mobility should decrease as a consequence of a larger hopping distance.