X-ray excited broadband blue emitting Lu2(1-x)Bi2xO3-PMMA thin films for high resolution imaging.

In this paper, cubic-phase Lu 2 O 3 :Bi3+ nanoparticles, with a range of sizes between 110 and 180 nm, were obtained by a combination of co-precipitation and thermal annealing techniques. For these nanoparticles upon UV or X-ray excitation, strong broadband emission peaks at 410 and 480 nm corresponding to Bi3+ occupying S 6 and C 2 (Lu3+(S 6) and Lu3+(C 2)) sites, respectively, can be observed. On the basis of the concentration-dependent luminescence intensity ratios (I 480 (C 2)/I 410 (S 6)) of Bi3+(C 2) to Bi3+(S 6), the energy transfer from Bi3+(S 6) to Bi3+(C 2) can be confirmed at high Bi3+ concentration. In particular, their X-ray absorption coefficient, emission wavelength, afterglow level (60 ppm) and response time (465 ns) are almost comparable to those of the commercial Bi 4 Ge 3 O 12 crystals. By the means of dispersing Lu 1.98 Bi 0.02 O 3 nanoscintillators into organic polymer (PMMA)-acetone solution, the Lu 1.98 Bi 0.02 O 3 -PMMA flexible composite films exhibiting rapid response to X-ray photons, high X-ray sensitivity and radiation resistance, good mechanical performance and excellent environmental stability were prepared using a spin-coating technique. On the surface of X-ray imaging screen formed by the flexible dense composite films, the spatial resolution can reach to 6.0 lp/mm at a safe irradiation dose (4.6 μGy). Meanwhile, for the imaging screen using the flexible composite films after bended for thousands of times, we can observe clear image of each reed gap (300 μm) of the music box. For the Lu 2 O 3 :Bi3+-PMMA composite films, our results suggest that not only their scintillation properties are almost comparable to those of the commercial broadband Bi 4 Ge 3 O 12 crystals, but also they might be applied in large-area and non-planar X-ray imaging. [ABSTRACT FROM AUTHOR]