Key points are not available for this paper at this time.
The mechanism of luminance decrease in blue emitting phosphor after annealing has been studied. It was shown experimentally that annealing in air oxidizes and substantially changes the ion to an ion. This is also deactivates the luminescent center, thus decreasing emission. Furthermore, the compound , in which the valence of the Eu ion is trivalent, was detected in annealed at temperatures higher than 800°C as a resulting product of oxidation. It was demonstrated that was converted by oxidation into a mixture of the two compounds and , and resulting in a further decrease in luminance. This suggests that obstructing the formation of during the annealing is essential for alleviating the decrease in luminance. Preparing having both superior crystallinity and completely stoichiometric composition has been found to be effective in alleviating the luminance decrease.
Oshio et al. (Sun,) studied this question.