Crystal-field Stark effect on the upconversion light emission spectrum of alpha-NaYF4 nanoparticles doped with Dy3+, Er3+, or Yb3+

Author(s)

Garcia-Flores, A. F. ; Martinez, E. D. ; Munevar, J. ; Garcia, D. J. ; Cornaglia, P. S. ; Fabris, F. ; Urbano, R. R. ; Rettori, C.

• Document type: Journal article
• Source: PHYSICAL REVIEW B; v. 106, n. 12, p. 9-pg., 2022-09-30.

Abstract

NaYF4 nanoparticles (NPs) form in two crystal structures, cubic (alpha-phase) and hexagonal (beta-phase), each one presenting a different crystal electric field (CEF) Stark effect, that affects the upconversion (UC) light emission of the NPs when doped with rare-earth elements. Therefore, the knowledge of the CEF parameters, the wave functions, and energy levels of the rare earth (RE) J-multiplet is expected to be of great help for the understanding and improvement of the UC light emission. In this work, alpha-phase NaYF4 NPs doped with Dy3+, Er3+, or Yb3+ were investigated by means of magnetization, electron spin resonance (ESR), and optical spectroscopy techniques. Fittings of the temperature-and magnetic-field-dependent magnetization were performed to determine the fourth-and sixth-order cubic CEF parameters, B4 and B6. The ground state of Er3+, Yb3+, and Dy3+ in these alpha-NaYF4 NPs was confirmed by low-temperature ESR experiments. The obtained CEF parameters were used to write down a total Hamiltonian that allows to determine the CEF Stark splitting for all energy levels of the REs 4 f unfilled shell. We give details of how the Stark effect affects the overall energy splitting of the various J-multiplets and may explain the fine structure of the UC light emission in these cubic NaY1-delta RE delta F4 NPs. (AU)

• FAPESP's process: 19/13678-1 - Magnetic properties of confined nanostructures: metallic and insulating rare-earth doped nanoparticles prepared by Laser Ablation and Chemical Syntheses.
• Grantee: Fernando Fabris
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/09673-4 - Technical and computational support for synthesis and characterization of metallic and insulator nanoparticles
• Grantee: Alí Francisco García Flores
• Support Opportunities: Scholarships in Brazil - Technical Training Program - Technical Training
• FAPESP's process: 18/21025-5 - Technical and computational support for synthesis and characterization of metallic and insulator nanoparticles
• Grantee: Alí Francisco García Flores
• Support Opportunities: Scholarships in Brazil - Technical Training Program - Technical Training
• FAPESP's process: 15/23882-4 - PLASMONIC EFICIENCY INTENSIFICATION OF THE UPCONVESION IN NANOCRYSTAIS DOPED WITH RARE EARTHS.
• Grantee: Eduardo David Martínez
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/10581-1 - Emergent phenomena in reduced dimension systems
• Grantee: Pascoal Jose Giglio Pagliuso
• Support Opportunities: Special Projects