Enhanced Blue Emission from Transparent Oxyfluoride Glass–Ceramics Containing Pr ³⁺ :BaF ₂ Nanocrystals

Transparent glass–ceramics containing Pr 3+ :BaF 2 nanocrystals in the chemical composition of SiO 2 –BaF 2 –K 2 CO 3 –La 2 O 3 –Sb 2 O 3 oxyfluoride glass systems have been prepared from melt quenching and with a subsequent heat‐treatment method. The luminescence and structural properties of these materials have been evaluated and the results are reported. Rietveld analysis of X‐ray diffraction patterns and investigation of transmission electron microscopy confirmed the presence of BaF 2 nanocrystals dispersed in the heat‐treated glass matrices. Measured UV‐Vis‐NIR absorption spectra exhibited nine bands of the transitions 3 H 4 → 3 P 2 , ( 1 I 6 , 3 P 1 ), 3 P 0 , 1 D 2 , 1 G 4 , 3 F 3 , 3 F 2 , 3 H 6 , and 3 H 5 from all the samples with nondegenerated 1 I 6 and 3 P 1 levels in the glass–ceramics. The photoluminescence spectra show an enhancement in the intensities upon ceramization, indicating the incorporation of Pr 3+ ions into BaF 2 nanocrystals that possess a low phonon energy (346 cm −1 ). This has further been corroborated from the observation of a significant threefold increase in the relative intensity ratio of blue ( 3 P 0 → 3 H 4 ) to red ( 1 D 2 → 3 H 4 , 3 P 0 → 3 H 6 ) emissions from glass–ceramics compared with the glass. This is due to a significant decrease of multiphonon nonradiative relaxation from the 3 P 0 to the 1 D 2 level of Pr 3+ in glass–ceramics. Time‐resolved spectra exhibit 3 P 0 ‐level decays faster than the 1 D 2 level.