Energy transfer, structural and luminescent properties of the color tunable phosphorY2WO6:Sm3+

D Espinoza, Neil L Allan, R Castillo, S Conejeros*, I Brito, I.R. Martin, P. Alemany, J. Llanos*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Inorganic phosphors based on monoclinic Y2WO6 doped with Sm3+ ions were prepared via conventional solid-state reactions at high temperature. A total of six samples were obtained with different Sm3+ concentrations (0–9%). The purity of the as-prepared phases was checked by powder X-ray diffraction (PXRD). The excitation, emission, and time-resolved emission spectra were examined in detail. The experimental decay curves were fitted to the Inokuti–Hirayama model, showing that the Sm3+ ions form clusters at all compositions. Periodic hybrid density functional theory calculations were also carried out on the undoped material and on 144-atom supercells of stoichiometry Y1.9375Sm0.0625WO6 and Y1.875Sm0.125WO6. The different coordination environments at the Y1, Y2 and Y3 sites are analysed in detail. The calculated structure and band gap of Y2WO6 are in good agreement with experiment with one potentially important discrepancy in a Y3-O bond length. The thermodynamically favoured substitution sites for Sm, Y2 and Y3, in the supercell are not those observed under the preparation conditions used here, since the experimental Rietveld analysis suggests occupation of Y1 at all concentrations. Analogous calculations for the Eu-doped system highlight marked differences between Eu and Sm despite their similar ionic sizes. The calculateddensities of states show the position of the 4f levels in the band gap depend on thesites occupied by the dopants and thus we expect marked differences in the luminescencespectra, opening up possibilities for tuning device performance.
Original languageEnglish
Article number155381
JournalJournal of Alloys and Compounds
Volume835
Early online date1 May 2020
DOIs
Publication statusE-pub ahead of print - 1 May 2020

Keywords

  • Inorganic materials
  • Solid State Reaction
  • Computer simulations
  • Luminescence
  • Optical properties
  • X-rah diffraction

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