Determination of the refractive index of BaY2F8:Er3+ (0.5 mol% to 30 mol%) in the 300 nm to 1800 nm range by ellipsometry; a record-breaking upconversion material

Joseph Gibbons, Callum M.s. Jones, Nick S. Bennett, Jose Marques-Hueso

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
23 Downloads (Pure)


This work reports the ellipsometric study of trivalent erbium (Er 3+) doped monocrystalline barium yttrium fluoride (BaY 2F 8), which has recently been shown to be one of the best photon upconversion (UC) materials available. This spans the BaY 2F 8 applications in a large range of wavelengths, from ultraviolet (UV) to near-infrared (NIR). We detail the optical properties of BaY 2F 8: Er 3+ (0.5 mol%, 10 mol%, and 30 mol%), measured via variable angle spectroscopic ellipsometry over a spectral range from 300 nm to 1800 nm, reporting for the first time the indices of refraction for BaY 2F 8:Er 3+. The upconversion external photoluminescence quantum yield (ePLQY) of the BaY 2F 8:Er 3+ samples have also been studied by exciting at [JG]λ=1588nmλ=1493 nm. The highest ePLQY of BaY 2F 8 was found for the largest dopant concentration 30 mol% Er 3+ reaching the value of [JG]1.07% ± 0.12%, at an irradiance of 9.512 ×10 −2W/cm 23.62% ± 0.01%, at an irradiance of (6.23 ± 0.45) ×10 −2 W/cm 2. The refractive index (λ= 589.3 nm) was determined to be 1.4808± 0.014 for 0.5 mol%, 1.4980± 0.003 for 10 mol%, and 1.5022± 0.006 for 30 mol%. Increasing Er 3+ doping concentration increased the refractive index. All samples decreased monotonically with increasing wavelength. The Brewster angle of BaY 2F 8:Er 3+ is observed to be ≈ 56 , whilst the Abbe number of the samples was found to be as high as 124.62. These findings provide valuable insight into the optical properties of BaY 2F 8:Er 3+ in the wide range of frequencies that is has proven useful.

Original languageEnglish
Article number117639
JournalJournal of Luminescence
Early online date20 Oct 2020
Publication statusPublished - Feb 2021


  • Barium yttrium fluoride
  • Refractive index
  • Spectroscopic ellipsometry
  • Upconversion material

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Chemistry(all)
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics


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