Role of Rare Earth Elements and Entropy on the Anatase-To-Rutile Phase Transformation of TiO2 Thin Films Deposited by Ion Beam Sputtering

Autor(es)

Scoca, Diego L. S. ^[1] ; Cemin, Felipe ^[1] ; Bilmes, Sara A. ^{[2, 3]} ; Figueroa, Carlos A. ^[4] ; Zanatta, Antonio R. ^[5] ; Alvarez, Fernando ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas UNICAMP, Inst Fis Gleb Wataghin, BR-13083970 Campinas - Brazil

^[2] Univ Buenos Aires, Fac Ciencias Exactas & Nat, C1428EGA, Ciudad De Buenos Aires C - Argentina

^[3] Univ Buenos Aires, Stituto Quim Mat Medio Ambiente & Energia INQUIMA, CONICET, C1428EHA, Ciudad De Buenos Aires C - Argentina

^[4] Univ Caxias DoSul UCS, Programade Posgrad Engn & Cienciados Mat, BR-95070560 Caxias Do Sul, RS - Brazil

^[5] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13566590 Sao Carlos - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ACS OMEGA; v. 5, n. 43, p. 28027-28036, NOV 3 2020.
• Citações Web of Science: 0

Resumo

The role played by oxygen vacancies and rare earth (RE) elements in the anatase-to-rutile (A-R) phase transformation of titanium dioxide (TiO2) is still a matter of controversy. Here, we report the A-R transformation of TiO2 thin solid films as obtained by ion beam sputtering a RE-decorated titanium target in an oxygen-rich atmosphere. The samples correspond to undoped, single-doped (Sm, Tm, and Tb), and codoped (Sm:Tb, Sm:Tm, and Sm:Tb:Tm) TiO2 films. In the as-prepared form, the films are amorphous and contain similar to 0.5 at. % of each RE. The structural modifications of the TiO2 films due to the RE elements and the annealing treatments in an oxygen atmosphere are described according to the experimental results provided by Raman scattering, X-ray photoelectron spectroscopy, and optical measurements. The A-R transformation depends on both the annealing temperature and the characteristics of the undoped, single-doped, and codoped TiO2 films. As reported in the literature, the A-R transformation can be inhibited or enhanced by the presence of impurities and is mostly related to energetic contributions. The experimental results were analyzed, considering the essential and stabilizing role of the entropy of mixing in the A-R transformation due to the introduction of more and multiple quantum states originated in vacancies and impurities in the anatase phase. (AU)

• Processo FAPESP: 12/10127-5 - Pesquisa e desenvolvimento de materiais nanoestruturados para aplicações eletrônicas e de física de superfícies
• Beneficiário: Fernando Alvarez
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 18/24461-0 - Estudo e desenvolvimento de filmes finos de ligas de alta entropia (LAE-F)
• Beneficiário: Felipe Cemin
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 19/18460-4 - Desenvolvimento e propriedades termomecânicas e tribológicas de materiais multicomponentes avançados de alta entropia
• Beneficiário: Fernando Alvarez
• Modalidade de apoio: Auxílio à Pesquisa - Regular