Development of oxyfluoroborate glass ceramics doped with Er3+ and Yb3+

The preparation of oxyfluoroborate glasses and glass-ceramics doped with Yb3+ and Er3+ with improved luminescent properties is reported. Glasses with compositions (100 - x - y) (MO center dot 2B(2)O(3)) + xPbF(2) + y(YbF3:ErF3) (% in mol), where M is Sr, Ba, Ca, x = 10-40% and y = 0, 1 or 5% were prepared by the melt/quenching technique. Glass crystallization was studied using thermal analysis and X-ray diffraction techniques. Optical absorption and infrared up-conversion were studied on both glasses and glass-ceramics. The incorporation of a fluoride compound into the borate glass resulted to depend on the ionic radius of the glass modifier: as it increases, glasses become more stable against crystallization. On the other hand, alkali-fluoride compounds such as BaF2 and SrF2 can be crystallized from these systems by selecting an appropriate proportion between their components. Furthermore, the up-conversion response can be tuned by changing the glass modifiers (Sr, Ba and Ca) of the borate matrix, which also influence the type of fluoride crystallized compound. The strontium glass-ceramics have the highest luminescence response due to the crystallization of SrF2 compound in the system SrO-B2O3-PbF2. Meanwhile, the lowest luminescence signal was obtained for samples in the system BaO-B2O3-PbF2 where the Pb1.33Ba2.66B11FO20 phase crystallizes. With this strategy, new materials with improved luminescence properties that can be used as up converters, were obtained.