Artículo
Experimental and theoretical interpretation of the order/disorder clusters in CeO2:La
Silva Rosa Rocha, Leandro; Aparecido Ciola Amoresi, Rafael; Marinho Duarte, Thiago; Marana, Naiara Letícia; Sambrano, Julio Ricardo; Aldao, Celso Manuel
; Zirpoli Simões, Alexandre; Ponce, Miguel Adolfo
; Longo, Elson
Fecha de publicación:
04/2020
Editorial:
Elsevier Science
Revista:
Applied Surface Science
ISSN:
0169-4332
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
A spectroscopic study of nanostructured lanthanum-doped cerium oxide samples showed that a mild decrease by5.3% in the surface concentration of Ce(III) species and, a reduction by 0.2 eV in the so-called energy-gap (EF ?Ev) after lanthanum addition was sufficient to create the previously reported significant dual behavior whenexposed to carbon monoxide at 653 K. The observed X-ray diffraction patterns indicated the presence of a purefluorite-type crystalline structure. A higher presence of paramagnetic defects clusters, indicated by electronparamagnetic resonance spectroscopy measurements and confirmed by the X-ray photoelectron spectroscopy,was attributed as being responsible for its dual behavior in a CO(g) atmosphere. Theoretical studies have shownthe band structure and density of state of the pure and doped material, illustrating the orbitals that participate inthe valence band and conduction band. The addition of a small quantity of La3+ converted some Ce3+ into Ce4+,narrowed the ?effective band-gap? by 0.2 eV, and created a singly ionized oxygen vacancy species, thus changingthe total electrical resistance and creating its dual behavior. The exposure to a reducing atmosphere such ascarbon monoxide resulted in a significant increase in defects and converted some Ce4+ into Ce3+ and vice-versawith oxygen atmosphere exposure.
Palabras clave:
DEFECTS
,
LANTHANUM
,
CERIUM OXIDE
,
CARBON MONOXIDE
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Articulos(INTEMA)
Articulos de INST.DE INV.EN CIENCIA Y TECNOL.MATERIALES (I)
Articulos de INST.DE INV.EN CIENCIA Y TECNOL.MATERIALES (I)
Citación
Silva Rosa Rocha, Leandro; Aparecido Ciola Amoresi, Rafael; Marinho Duarte, Thiago; Marana, Naiara Letícia; Sambrano, Julio Ricardo; et al.; Experimental and theoretical interpretation of the order/disorder clusters in CeO2:La; Elsevier Science; Applied Surface Science; 510; 4-2020; 1-11
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