Electric Properties Change during Morphological Evolution of CeO2 Nanostructures: Synergy between Bulk and Surface Defects

Carlos Macchi; Alley M S Procópio; Leandro S R Rocha; Pedro P Ortega; Celso M Aldao; Luis I Granone; Hugo M S Nascimento; Elson Longo; Miriam S Castro; Fernando D Ivorra; Alberto Somoza; Francisco Moura; Miguel A Ponce

doi:10.1021/acsomega.4c03210

Electric Properties Change during Morphological Evolution of CeO₂ Nanostructures: Synergy between Bulk and Surface Defects

ACS Omega. 2024 Oct 3;9(41):42172-42182. doi: 10.1021/acsomega.4c03210. eCollection 2024 Oct 15.

Authors

Affiliations

¹ CIFICEN (UNCPBA-CICPBA-CONICET) and Materials Physics Institute (IFIMAT), National University of Central Buenos Aires (UNCPBA), Tandil 7000, Argentina.
² Advanced Materials Interdisciplinary Laboratory (LIMAv), Federal University of Itajubá, Itabira, Minas Gerais 35903-087, Brazil.
³ Materials Engineering Department, Federal University of São Carlos (UFSCar), São Carlos, São Paulo 13565-905, Brazil.
⁴ Center for Research and Development of Functional Materials (CDMF), Federal University of São Carlos (UFSCar), São Carlos, São Paulo 13565-905, Brazil.
⁵ Institute of Scientific and Technological Research in Electronics (ICYTE), University of Mar del Plata and National Research Council (CONICET), Mar del Plata B7608FDQ, Argentina.
⁶ Departamento de Química y Bioquímica, Facultad de Ciencias Exactas y Naturales, Instituto de Investigaciones Físicas de Mar del Plata (IFIMAR), CONICET, Universidad Nacional de Mar del Plata (UNMDP), Mar del Plata 7600, Argentina.
⁷ Institute of Materials Science and Technology (INTEMA), National University of Mar del Plata and National Scientific and Technical Research Council (CONICET), Mar del Plata 7600, Argentina.

Abstract

CeO₂ samples were synthesized via the polymeric precursor method at different calcination temperatures. Electric properties were investigated using positron annihilation lifetime spectroscopy, electron paramagnetic resonance spectroscopy, and complex impedance spectroscopy. Reduction in the specific surface area of the particles with increasing calcination temperature along with morphological changes were observed. PALS depicted doubly ionized oxygen vacancies surrounded by two Ce3+ atoms, while the EPR spectroscopy showed a singly ionized oxygen vacancy surrounded by Ce3+ and Ce4+ ions. Impedance measurements unraveled the presence of polarons, while thermal treatments led to a lower electrical conductance, as the calcination temperature increased.