Novel rare-earth doped fluorides and process for preparing

摘要

The invention is directed a composition represented by the chemical formula Eu x A 1-x F 2+x-2y O y wherein A is alkaline earth, 0.002 ‰ x ‰ 0.20, and 0 ‰ y ‰ x; the composition exhibiting a luminescence spectrum characterized by peaks at 592 ± 2 nm and 627 ± 2 nm, wherein the ratio of the peak intensity at 592 ± 2 nm to that at 627 ± 2 nm is at least 5% larger than the corresponding peak intensity ratio at the same wavelengths of a first corresponding reference composition with the same value of x that has not been exposed to a temperature above 100°C, and wherein said ratio of the peak intensity at 592 ± 2 nm to that at 627 ± 2 nm is at least 5% smaller than the corresponding peak intensity ratio at the same wavelengths of a second corresponding reference composition with the same value of x that has been subject to heating to 900°C for 6 hours.