Green Synthesis of Upconverting NaYF4 and NaGdF4 Materials and Energy Levels Determination

Author(s)

Giordano, Luidgi ^[1] ; Nunes, Matheus F. ^[1] ; Teixeira, Veronica C. ^[2] ; Rodrigues, Lucas C. V. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, BR-05508000 Sao Paulo, SP - Brazil

^[2] Ctr Nacl Pesquisa Energia & Mat CNPEM, Lab Nacl Luz Sincrotron LNLS, BR-13083970 Campinas, SP - Brazil

• Document type: Journal article
• Source: Journal of the Brazilian Chemical Society; v. 32, n. 8, p. 1552-1558, AUG 2021.
• Web of Science Citations: 0

Abstract

An alternative green route using a domestic microwave oven to synthesize NaGdF4:Yb,Tm and NaYF4:Yb,Er was successfully developed. Decreasing dopants concentration increased the β-NaREF4/α-NaREF4 ratio in NaGdF4. The scanning electron microscopy (SEM) images of NaGdF4 showed particles ranging from 500 nm to 1 μm with formation of aggregates up to 100 μm, with two different surface morphologies. The NaGdF4:Yb,Tm emission spectrum showed white-like emission due to Er3+ and Eu3+ contamination. The bandgaps of undoped NaGdF4 and NaYF4 were measured using synchrotron radiation vacuum-UV (VUV) diffuse reflectance, with values of 10.20 eV for the cubic phase and 10.80 eV for the hexagonal phase for both materials. The determination of the RE2+/3+ energy level positions in these fluorides sheds new light on the design of efficient upconversion materials. (AU)

• FAPESP's process: 18/05280-5 - Red-Infrared active photonic materials for energy conversion and storage
• Grantee: Lucas Carvalho Veloso Rodrigues
• Support Opportunities: Regular Research Grants