Revealing the Nature of Defects in alpha-Ag2WO4 by Positron Annihilation Lifetime Spectroscopy: A Joint Experimental and Theoretical Study

Author(s):Show less -

Assis, Marcelo ^[1] ; Adolfo Ponce, Miguel ^[2] ; Fernandes Gouveia, Amanda ^{[3, 4]} ; Souza, Daniele ^[5] ; de Campos da Costa, Joao Paulo ^[1] ; Teodoro, Vinicius ^[1] ; Gobato, Yara Galvao ^[5] ; Andres, Juan ^[4] ; Macchi, Carlos ^{[6, 7]} ; Somoza, Alberto ^{[6, 7]} ; Longo, Elson ^[1]

Affiliation

^[1] Fed Univ Sao Carlos UFSCar, Chem Dept, LIEC, CDMF, BR-13565905 Sao Carlos, SP - Brazil

^[2] Inst Mat Sci & Technol INTEMA, RA-7600 Mar Del Plata, Buenos Aires - Argentina

^[3] Univ Estadual Campinas, Inst Chem, BR-13083970 Campinas, SP - Brazil

^[4] Univ Jaume I UJI, Dept Phys & Analyt Chem, Castellon de La Plana 12071 - Spain

^[5] Fed Univ Sao Carlos UFSCar, Phys Dept, BR-13565905 Sao Carlos, SP - Brazil

^[6] UNCPBA CICPBA CONICET, CIFICEN, B7000GHG, Tandil - Argentina

^[7] UNCPBA, Inst Fis Mat Tandil, B7000GHG, Tandil - Argentina

• Document type: Journal article
• Source: Crystal Growth & Design; v. 21, n. 2, p. 1093-1102, FEB 3 2021.
• Web of Science Citations: 0

Abstract

Electronmatter coupling is a fascinating way to tune and modify the properties of materials. In this work, we present a study on the formation and nature of vacancy-like defects in a-Ag(2)WO4 samples synthesized in a water or ethanol medium and subsequently submitted to electron beam irradiation at different exposure times. To understand the effects on the geometrical and electronic nature of the generated defects, the data obtained by positron annihilation lifetime spectroscopy were interpreted with the aid of first-principles calculations at the density functional theory level. To complement these results, X-ray diffraction, Raman spectroscopy, photoluminescence emissions, and field emission gun scanning electron microscopy techniques were also used. Based on the positron binding energy and the calculated and experimental positron lifetimes, the defect structure of the nonirradiated and irradiated samples was revealed. As a general feature, it was found that the defect structure is more complex for samples synthesized in ethanol than in water. In particular, the results show that all samples contain defects involving Ag vacancies and that the concentration of this type of defect increases with the irradiation time. (AU)

• FAPESP's process: 19/01732-1 - Photocatalytic activity of multifunctional semiconductors: influence of morphology and electron injection
• Grantee: Amanda Fernandes Gouveia
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
• Grantee: Elson Longo da Silva
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC