Optical and X-ray induced luminescence from Eu3+ doped La2Zr2O7 nanoparticles

Nanocrystalline complex oxide scintillators have emerged for use in X-ray and gamma-ray detection in recent years. Here the doping concentration dependence of europium-doped lanthanum zirconate (La2Zr2O7:xmol%Eu3+, x = 1 to 35) nanoparticles (NPs) were investigated by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), and optically and X-ray excited luminescence. Spectroscopic methods revealed a gradual increase in disorder from the ordered pyrochlore structure to the defect fluorite structure as the Eu3+ concentration increases. They showed red luminescence under charge transfer band (258 nm), and Eu3+ 4f-4f bands (322, 394 and 465 nm) excitation with optical intensity dependent on the Eu3+ doping concentration and not quenching up to 5% Eu3+ doping concentration. The quantum yield of the red emission was found to depend on the Eu3+ doping concentration and excitation wavelength. Moreover, these La2Zr2O7:x%Eu3+ NPs demonstrated an atypical Eu3+ related scintillating response with a red emission under high-energy X-ray excitation with the scintillation intensity also depending on the Eu3+ doping concentration. Finally, the irradiation damage behavior induced by the excitation source was representatively examined for the La2Zr2O7:5%Eu3+ NPs. It is expected that the current study will pave the way for future research of nanoscintillators.