Tuning the magnetic properties of Sn1-x-yCe4+xCe3+yO2 nanoparticles: an experimental and theoretical approach

Author(s)

Aragon, F. F. H. ^[1] ; Villegas-Lelovsky, L. ^{[2, 3]} ; Cabral, L. ^[4] ; Lima, M. P. ^[3] ; Mesquita, A. ^[2] ; Coaquira, J. A. H. ^{[5, 1]}

Affiliation

^[1] Univ Nacl San Agustin Arequipa, Lab Peliculas Delgadas, Escuela Profes Fis, Ave Independencia S-N, Arequipa - Peru

^[2] Univ Estadual Paulista, Dept Fis, IGCE, BR-13506900 Rio Claro, SP - Brazil

^[3] Univ Fed Sao Carlos, Ctr Ciencias Exatas & Tecnol, Dept Fis, BR-13565905 Sao Carlos, SP - Brazil

^[4] Univ Estadual Campinas, Inst Fis Gleb Wataghin IFGW, BR-13083859 Campinas, SP - Brazil

^[5] Univ Brasilia, Nucleo Fis Aplicada, Inst Fis, BR-70910900 Brasilia, DF - Brazil

• Document type: Journal article
• Source: NANOSCALE ADVANCES; v. 3, n. 5, p. 1484-1495, MAR 7 2021.
• Web of Science Citations: 0

Abstract

During the last decade, there was a substantial increase in the research on metal-doped oxide semiconductor nanoparticles due to advances in the engineering of nanomaterials and their potential application in spintronics, biomedicine and photocatalysis fields. In this regard, doping a nanomaterial is a powerful tool to tune its physicochemical properties. The aim of this work is to shine a new light on the role of the neighbouring elements on the oxidation state of the Ce-impurity, from both experimental and theoretical points of view. Herein, we present an accurate study of the mechanisms involved in the oxidation states of the Ce-ions during the doping process of SnO2 nanoparticles (NPs) prepared by the polymeric precursor method. X-ray diffraction measurements have displayed the tetragonal rutile-type SnO2 phase in all samples. However, the Bragg's peak (111) and (220) located at 2 theta similar to 29 degrees and similar to 47 degrees evidence the formation of a secondary CeO2 phase for samples with Ce content up to 10%. X-ray absorption near-edge structure (XANES) measurements, at Ce L3 edge, were performed on the NPs as a function of Ce content. The results show, on one side, the coexistence of Ce3+ and Ce4+ states in all samples; and on the other side, a clear reduction in the Ce3+ population driven by the increase of Ce content. It is shown that this is induced by the neighboring cation, and confirmed by magnetic measurements. The monotonic damping of the Ce3+/Ce4+ ratio experimentally, was connected with theoretical calculations via density functional theory by simulating a variety of point defects composed of Ce impurities and surrounding oxygen vacancies. We found that the number of oxygen vacancies around the Ce-ions is the main ingredient to change the Ce oxidation state, and hence the magnetic properties of Ce-doped SnO2 NPs. The presented results pave the way for handling the magnetic properties of oxides through the control of the oxidation state of impurities. (AU)

• FAPESP's process: 13/12993-4 - Synthesis and characterization of luminescent nanostructured semiconductor materials
• Grantee: Alexandre Mesquita
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/02317-2 - Interfaces in materials: electronic, magnetic, structural and transport properties
• Grantee: Adalberto Fazzio
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/20729-9 - Formation of Ag Nanoparticles by Laser Irradiation: An ab inicio Investigation
• Grantee: Luis Antônio Cabral
• Support Opportunities: Scholarships in Brazil - Post-Doctoral