Structural, photoluminescence and radioluminescence properties of Eu3+ doped La2Hf2O7 nanoparticles

This study presents the structural, optical, and radioluminescent characterization of newly synthesized europium-doped lanthanum hafnate (La2Hf2O7:xmol%Eu3+, x=0 to 35) nanoparticles (NPs) for use as phosphors and scintillation materials. Samples prepared through a combined co-precipitation and molten salt synthetic process were found to crystalize in the pyrochlore phase, a radiation tolerant structure related to the fluorite structure. These samples exhibit red luminescence under ultraviolet and X-ray excitation. Under these excitations, the optical intensity and quantum yield of the La2Hf2O7:xmol%Eu3+ NPs depend on the Eu3+ concentration and are maximized at 5%. It is proposed that there is a trade-off between the quenching due to defect states/cross-relaxation and dopant concentration. An optimal dopant concentration allows the La2Hf2O7:5 mol%Eu3+ NPs to show the best luminescent properties of all the samples.