Thin-film structure and fluorescence properties of sol-gel-synthesized Y2-xEuxO3 phosphors

Abstract

Eu-doped yttria (Y 2¹x Eu x O 3 ) thin-film phosphors were prepared using a solgel process with post-annealing at 900°C. The Y 2¹x Eu x O 3 samples showed cubic bixbyite structure with a gradual increase in the lattice constant (¯0.5%) as x increases (¯0.22). The Eu-doped films exhibited strong photoluminescence (PL) near 2 eV at room temperature with well-resolved fluorescence peaks being ascribed to spin-flip f-f transitions,) ion. Among the six fluorescence lines, the intensity of the strongest 2.03-eV line (J = 2) varies significantly with the Eu content and its optimum value for the maximum PL strength is likely to be near x = 0.1. The Eu-doped films on the Al 2 O 3 substrates exhibited significantly higher PL intensities than those on the Si substrates despite no significant difference in structural properties between the two species being observed. It can be understood by comparing the change of complex refractive index for the Y 2¹x Eu x O

Photo- and Radioluminescence Properties of Eu3+-doped Y2O3 Thick Film Phosphor Prepared via Chemical Vapor Deposition

“…From the cross-sectional SEM image and deposition time, the deposition rate was calculated to be 42 μm h −1 , which was 840-10500 times higher than those of Eu 3+ :Y 2 O 3 thin films prepared using the sol-gel (0.05 μm h −1 ), CVD (0.004 μm h −1 ), and chemical bath deposition (0.004 μm h −1 ) methods. (15)(16)(17) Figure 2(b) shows the in-line transmittance spectra of the Eu 3+ :Y 2 O 3 thick film on the YSZ substrate and the raw YSZ substrate. The in-line transmittance of the Eu 3+ :Y 2 O 3 thick film at a wavelength of 600 nm was 81% of that of the raw YSZ substrate.…”

“…(12) Eu 3+ -doped Y 2 O 3 (Eu 3+ :Y 2 O 3 ) has a high light yield (32000 ph MeV −1 ) with red emission (612 nm) that well matches CCD detectors. (13) However, large Y 2 O 3 single crystals cannot be easily grown because of the high melting point (2700 K) and the transition from the hexagonal to cubic phase at 2600 K. (14) Although Eu 3+ :Y 2 O 3 thin films of up to 50 nm thickness have been prepared by the sol-gel, chemical bath deposition, and CVD methods, (15)(16)(17) they are too thin to stop radiation. From Henke's table, the mean free path of 8 keV X-rays in Y 2 O 3 crystal has been calculated to be 7 μm.…”

Structure and morphological stability of (Lu1–xEux)2O3 thin films

“…In addition, control of physical and chemical parameters at each stage of film preparation provides homogeneity of the final products, optical transparency and a uniform distribution of the activator ions in the phosphor matrix. The conventional dip‐coating or spin‐coating technologies with subsequent heat treatment allow films with controlled thickness and a perfect degree of the surface homogeneity to be obtained .…”