White light emitting LaGdSiO5:Dy3+ nanophosphors for solid state lighting applications

Simon N. Ogugua, Hendrik C. Swart, Odireleng M. Ntwaeaborwa

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Powdered dysprosium (Dy3+) doped Lanthanum gadolinium oxyorthosilicate (LaGdSiO5) mixed phosphors were synthesized using urea-assisted solution combustion method. The X-ray diffractometer analysis showed that the samples crystalized in the pure monoclinic mixed phase of LaGdSiO5. The crystallite size and the lattice strain calculated from the X-ray diffraction peaks using Williamson-Hall equation varied from 12 nm to 16 nm and 1.6×10-2 to 2.43×10-2 respectively. The photoluminescence (PL) emission spectra recorded using 425, 454 and 475 nm excitation wavelengths exhibit characteristic similar to the YAG:Ce phosphor pumped InGaN LED system, by absorbing portion of the excitation energy and re-emitting it. The emission spectra were characterized by radiative recombination at 425, 454, 475, 485 and 575 nm depending on the excitation wavelength. These emission line are ascribed to the f→f transitions of Dy3+. The peak intensity and hence the color of the emitted visible light were dependent on the concentration of Dy3+. The International Commission on Illumination (CIE) color coordinates of (0.336, 0.313) and (0.359, 0.361) were obtained for Dy3+ molar concentration of 0.05 and 3.0 mol% when the emission was monitored using 454 nm and 475 nm respectively. The band gap measured from the reflectance curve using Tauc plot initially decreased with increasing Dy3+ concentration, but at higher concentration, it started to increase. These materials were evaluated for solid state lighting application.

Original languageEnglish
Pages (from-to)131-136
Number of pages6
JournalPhysica B: Condensed Matter
Volume480
DOIs
Publication statusPublished - 1 Jan 2016
Externally publishedYes

Keywords

  • Oxyorthosilicates
  • Phosphors
  • Photoluminescence
  • Solid State Lighting

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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