O.A. Graeve, S. Varma, G. Rojas-George, D. Brown, and E.A. Lopez, "Synthesis and Characterization of Luminescent Yttrium Oxide Doped with Tm and Yb," Journal of the American Ceramic Society, 89 [3] 926-931 (2006).

Combustion synthesis was used to obtain nanocrystalline Y_(2-x-y) Tm_xYb_yO₃ blue-emitting phosphors. From X-ray diffraction (XRD) it was determined that the powders in the as-synthesized state were in a state of high strain. Upon thermal treatment, the strain in the lattice decreased, which resulted in an improvement in the photoluminescence emission intensity of these phosphors. Fourier-transform infrared spectrometry analysis showed that there is a negligible difference in the absorbed impurities with heat-treatment temperature and time. Hence, it was concluded that the surface impurities do not play a role in the increase in luminescence intensity of these phosphors. The optimum activator concentrations were determined to be approximately x = 0.02 and y = 0.01.