Optical properties and Judd-Ofelt analysis of Dy3+ doped CoAl2O4 nanocrystals

CoAl2O4:xDy(3+) nanocrystals (x = 0, 0.1, 0.5, 1.0, and 3.0 mol%) with spinel structures were prepared using the co-precipitation method. The crystal structure, optical properties, and presence of elements were respectively analyzed using X-ray diffraction, photoluminescence excitation, photoluminescence spectra, luminescence lifetime, and X-ray photoelectron spectroscopy. The influence of temperature on material fabrication was studied using differential scanning calorimetry and thermogravimetric techniques. The color characteristics of Dy3+ luminescence in the CoAl2O4 host were evaluated using CIE chromaticity coordinates and correlated color temperature. For the first time, the electronic dipole transitions in the photoluminescence excitation spectra were used to calculate the optical parameters of Dy3+ ions in the CoAl2O4 host using Judd-Ofelt theory. The Inokuti-Hirayama model was used to explain the energy transfer process between Dy3+ ions, the main interaction mechanism, and energy transfer parameters for the luminescence of Dy3+ ions.