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

Abstract

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%Eu 3+ , 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 Eu 3+ concentration increases. They showed red luminescence under charge transfer band (258 nm), band gap (322 nm), and Eu 3+ 4f-4f bands (394 and 465 nm) excitation with optical intensity dependent on the Eu 3+ doping concentration and not quenching up to 5% Eu 3+ doping concentration. The quantum yield of the red emission was found to depend on the Eu 3+ doping concentration and excitation wavelength.Moreover, these La2Zr2O7:x%Eu 3+ NPs demonstrated an atypical Eu 3+ related scintillating response with a red emission under high-energy X-ray excitation with the scintillation intensity also depending on the Eu 3+ doping concentration. Finally, the irradiation damage behavior induced by the excitation source was representatively examined for the La2Zr2O7:5%Eu 3+ NPs. It is expected that the current study will pave the way for future research of nanoscintillators.

Synthesis and photocatalytic properties of sunlight‐responsive BiOBr–CoWO4 heterostructured nanocomposites

“…Increasing the CoWO 4 content in BiOBr reduces the fluorescence lifetime of the composites. Similar effects were reported by Pokhrel et al . The decay curves of the BiOBr–CoWO 4 nanocomposites revealed that energy transfer and decay processes were dependent on the amount of CoWO 4 nanoparticles in the composite.…”

On comparison of luminescence properties of La2Zr2O7 and La2Hf2O7 nanoparticles

“…These properties make them suitable for scientific and technological applications such as thermal barrier coatings, magnetic materials, electrocatalysis, sensors, optical materials, solid‐oxide fuel cells, high level nuclear waste hosts, etc. Moreover, recently relevant nanostructured pyrochlore materials have gained significant attention compared with their bulk counterparts in the areas of photoluminescence, scintillation, and magnetism …”

“…They are thermally stable, can accommodate dopant ions at both A and B sites, and have high radiation stability, etc. Hence, they are predominately used as hosts in the production of doped inorganic phosphors . Moreover, lanthanum‐based pyrochlores are known to exhibit excellent thermal stability, high thermal shock resistance, and fracture toughness compared to ytrria‐stabilized zirconia (YSZ) .…”

“…Recent studies on zirconate based phosphors show that, Zr 4+ exists in d 0 configuration play a very decisive role in ligand to metal charge transfer (LMCT) . There are only a few independent reports on the luminescence studies of La 2 X 2 O 7 :Eu 3+ (X = Zr and Hf), but comparative studies for the observed differences are missing, not to mention the understanding of the underlying mechanisms both experimentally and theoretically, including the energetics of ionized oxygen vacancies, the host to dopant energy transfer, and non‐radiative channels …”

“…These properties make them suitable for scientific and technological applications such as thermal barrier coatings, 1 magnetic materials, 2,3 electrocatalysis, 4,5 sensors, 6 optical materials, 7 solid-oxide fuel cells, 8 high level nuclear waste hosts, 9 etc. Moreover, recently relevant nanostructured pyrochlore materials have gained significant attention compared with their bulk counterparts in the areas of photoluminescence, [10][11][12][13] scintillation, [11][12][13] and magnetism. 14 In this context, La 2 Zr 2 O 7 and La 2 Hf 2 O 7 have been two standout pyrochlores for their suitability in various kinds of technological applications such as luminescence, scintillator, ferroelectric material, nuclear waste host, catalyst, and electrode material in fuel cells, etc.…”