Designing luminescent materials especially nanomaterials with multifunctional applications is highly challenging and demanding. In this work, we explored pyrochlore La2Hf2O7 nanoparticles (NPs) singly and triply codoped with Eu3+, Tb3+ and Dy3+. Under both ultraviolet and X-ray irradiations, the La2Hf2O7 NPs singly doped with Eu3+, Tb3+ and Dy3+ displayed red, green and yellowish-blue emission, respectively. The concentration quenching study revealed a non-radiative energy transfer in Eu3+ doped La2Hf2O7 NPs, which takes place via dipole-quadrupole mechanism. On the other hand, a dipole-dipole interaction prevails in Tb3+ and Dy3+ doped La2Hf2O7 NPs. Lifetime spectroscopy reveals the stabilization of Eu3+ and Dy3+ ions at La3+ site at low doping concentration whereas a fraction of them migrates to Hf4+ site at high doping concentration. For the La2Hf2O7:Tb3+ NPs, Tb3+ ions are localized at Hf4+ site at all doping concentrations. Furthermore, when triply codoped with Eu3+, Tb3+ and Dy3+ ions, the La2Hf2O7 NPs display beautiful warm white light as a new strategy for color tunability through doping percentage. To sum, our complete spectrum of studies on the structure, UV excited photoluminescence, concentration quenching, and local site spectroscopy of the La2Hf2O7:Ln3+ NPs suggests that they are potential candidates as single-component multicolor-emitting phosphors for lighting and scintillating applications.
Gupta, Santosh K., et al. "Lanthanide-doped lanthanum hafnate nanoparticles as multicolor phosphors for warm white lighting and scintillators." Chemical Engineering Journal 379 (2020): 122314.doi:10.1016/j.cej.2019.122314.
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