Flux-Aided Synthesis of Lu2O3 and Lu2O3:Eu—Single Crystal Structure, Morphology Control and Radioluminescence Efficiency

Abstract

Li2SO4 or (Li2SO4 + SiO2)-mixture fluxes were used to prepare a Lu2O3:Eu powder phosphor as well as an undoped Lu2O3 utilizing commercial lutetia and europia as starting reagents. SEM images showed that the fabricated powders were non-agglomerated and the particles sizes varied from single microns to tens of micrometers depending largely on the flux composition rather than the oxide(s)-to-flux ratio. In the presence of SiO2 in the flux, certain grains grew up to 300–400 μm. The lack of agglomeration and the large sizes of crystallites allowed making single crystal structural measurements and analysis on an undoped Lu2O3 obtained by means of the flux technique. The cubic structure with a = 10.393(2) Å, and Ia space group at 298 K was determined. The most efficient radioluminescence of Lu2O3:Eu powders reached 95%–105% of the commercial Gd2O2S:Eu.

Bright Lu2O3:Eu Thin‐Film Scintillators for High‐Resolution Radioluminescence Microscopy

“…An X-ray excited photoemission spectrum of the deposited film confirms the presence of Lu 2 O 3 :Eu, as demonstrated by the 610 nm peak corresponding to the 5 D 0 → 7 F 2 transition (Figure 2b), corresponding to observed spectra in literature. [15] Other transitions are also annotated. Transparency measurements (Figure S1) for substrates to be used for vapor deposition indicate that a sapphire substrate is a more transparent substrate, and performs better than silica.…”

Radio-, Thermo- and Photoluminescence Properties of Lu2O3:Eu and Lu2O3:Tb Nanopowder and Film Scintillators

“…The structure and morphology of NPs and films were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Measured XRD patterns of the Lu 2 O 3 :Eu and Lu 2 O 3 :Tb powders are presented in Figure 1 together with a simulated pattern ICSD#40471 of Lu 2 O 3 [3]. Analogous data were collected for films.…”

“…The Lu 2 O 3 lattice provides two positions with different symmetry of Lu 3+ cations and consequently also of the Eu 3+ and Tb 3+ dopants [3]. These are centrosymmetric C 3i (often termed S 6 in the spectroscopic literature which is not fully correct) and lower-symmetry non-centrosymmetric C 2 sites.…”

“…The population of the latter is triple the population of the former. Generally speaking, for the C 3i sites the electric dipole 4f-4f transitions are forbidden and emission spectra of the Lu 2 O 3 :Eu and Lu 2 O 3 :Tb NPs are dominated by transitions of Eu 3+ and Tb 3+ ions occupying the C 2 sites [2,3] unless direct selective excitation into the dopant in the C 3i site is applied. Furthermore, at least for the Eu 3+ activator, significant Eu(C 3i )→Eu(C 2 ) energy transfer occurs when the dopant content increases abovẽ 1 mol% [2].…”

“…Eu 3+ and Tb 3+ doped Lu 2 O 3 oxides are mostly researched as sintered ceramics and nanocrystalline powder (NP) X-ray phosphors [1][2][3]. Due to its extremely high density of 9.42 g/cm 3 (one of the densest inorganic compounds) and high effective Z-number Z eff = 67.3, Lu 2 O 3 -based phosphors attract attention as film scintillating screens for 2D/3D microimaging using X-ray or synchrotron radiation [4,5]. However, the properties of these materials in the various crystalline forms were found to be influenced by the differences in the methods and conditions of their preparation [6].…”