Studies of the spectroscopic properties of lead–gallium oxyfluoride (LGOF) glasses and glass–ceramics activated by Pr 3+ ions

White light and near-infrared emissions of Pr3+ ions in SiO2-LaF3 sol–gel nano-glass-ceramics

“…As could be seen, for the as-prepared xerogels, the luminescence of Pr 3+ was not recorded, contrary to various types of Pr 3+ -doped glasses prepared by the conventional melt-quenching method, as presented in numerous papers published elsewhere. 1,30,32,33,36,38,[40][41][42] The observed quenching of Pr 3+ emission in xerogels is strictly correlated with the occurrence of plentiful high-vibrational OH groups inside the silicate pores of the sol-gel network, which are responsible for the fast and efficient quenching of the Pr 3+ luminescence from the emitting 3 P 0 and 1 D 2 levels, considering the relatively small 3 P 0 -1 D 2 (∼4080 cm −1 ) and 1 D 2 -1 G 4 (∼6570 cm −1 ) energy gaps.…”

“…Most of the Pr 3+ -doped OxGC materials characterized and described in the current literature are focused on the preparation by high-temperature melt-quenching method, followed by the annealing of parent glasses at controlled and specified time and temperature conditions. Among them, OxGCs containing plentiful fluoride phases classified to AF x type (CaF 2 , 29 SrF 2 , 30,31 BaF 2 , 32,33 LaF 3 , 2,34–37 YF 3 , 38 or PbF 2 39 ) and AMF x type (NaYF 4 , 1 NaLaF 4 , 25 BaYF 5 , 40 LiGdF 4 /GdF 3 , 41 NaGdF 4 , 42 KYF 4 43 ) have been reported. Interestingly, the spectroscopic behavior of Pr 3+ ions could be successfully modulated by changing their local environment, i.e.…”

“…Interestingly, the spectroscopic behavior of Pr 3+ ions could be successfully modulated by changing their local environment, i.e., glassy or crystalline. In this matter, C. Koepke et al 32 reported that Pr 3+ photoluminescence in BaF 2 -based OxGCs is strictly correlated to their residing in oxide higher-field (O-Pr-O) or fluorine lower-field (F-Pr-F and/or O-Pr-F) sites. Further, for KYF 4 :Pr 3+ -based glass-ceramics, it was proven that the modification in a local field around Pr 3+ from fully amorphous to crystalline (for the latter with parallel controll of the growth of fluoride crystals from 5 nm to 30 nm) resulted in emission color tuning from red via warm white, finally to cold white.…”