Abstract:

Pr³⁺-activated 50SiO₂ -10AlF₃-5TiO₂-30BaF₂-4LaF₃ glass were synthesized by a conventional melting technique, and then annealed at 640℃, 660℃ and 690℃, respectively. Transparent Ba₂LaF₇: Pr³⁺ glass ceramics were successfully prepared and the transparency still remained at a high level. X-ray diffraction and transmission electron microscope were used to monitor the evolution and microstructural changes after the glass specimens were annealed at temperature increasing from 640℃ to 690℃. The spectral properties of glass and glass ceramics were also investigated. Results show that Ba₂LaF₇ nanocrystals were precipitated in the teat-treated glasses and the measured luminescent properties indicate that Pr³⁺ ions are gradually incorporated into the precipitated Ba₂LaF₇ crystalline phase. Under 443 nm excitation, the Commission Internationale de L’Eclairage (CIE) chromaticity coordinates for the glass ceramics heated at 660 ℃, were estimated to be (0.323, 0.343) and exactly located in the region of white light. Current findings reveal a fact that the prepared materials have potential as replacements of commonly employed phosphors applicating in white light-emitting diodes.

Key words: Ba₂LaF₇: Pr³⁺, glass ceramics, luminescent properties