Structural properties and luminescence dynamics of CaZrO3:Eu3+ phosphors

Abstract

In the present work, the effect of Eu³⁺ doping concentration on the structural and luminescence properties of Eu³⁺ doped CaZrO₃ red phosphors was investigated. The phase purity and structural properties of the synthesized phosphors were studied by the Rietveld refinement method. Rietveld refinement confirms the occupancy of Eu³⁺ ions at the Ca²⁺ site in the CaZrO₃ host. Furthermore, extended X-ray absorption fine structure spectroscopy and photoluminescence spectroscopy were used to explore the local structure around Eu³⁺ ions and the location of Eu³⁺ ions. An extensive investigation on luminescence properties explored the UV-blue and sharp red emissions; and tuning of the colour with systematic doping concentration. The most bright red emission was achieved at 3 mol% Eu³⁺ doping concentration. The luminescence excitation–emission process and energy transfer mechanism were well depicted. The extensive luminescence investigation illustrated the origin of the UV-blue emission and the role of charge compensation in the luminescence phenomenon. Finally, the density of states (DOS) calculation using density functional theory has been introduced as a complementary investigation to support the modelling of the luminescence mechanism. DOS indicated the role of oxygen vacancy in the origin of UV-blue emission from the CaZrO₃ host material and the energy transfer process. The correlation between structural and luminescence properties has been well illustrated in this article. The excited state lifetime and host to dopant energy transfer efficiency were studied with the Eu³⁺ doping concentration. Small excited state lifetime and colour coordinates indicate the possibility of pink-red emitting 3 mol% Eu³⁺ doped CaZrO₃ as a suitable candidate for light-emitting device applications.