Structural Studies of Fluoroborate Laser Glasses by Solid State NMR and EPR Spectroscopies

The structure of glasses in the systems (100 – x )B 2 O 3 – x PbF 2 ( x = 30, 40, and 50) and 50B 2 O 3 –(50 – x )PbO– x PbF 2 ( x = 5, 10, 15, 20, 25, 30, 35, 40, and 45) has been studied by solid state NMR and EPR spectroscopies. On the basis of 11 B and 19 F high resolution solid state NMR as well as on 11 B/ 19 F double resonance results, we develop a quantitative structural description on the atomic scale. 19 F NMR results indicate a systematic dependence of the fluoride speciation on PbF 2 content: At low x -values, F – ions are predominantly found on BO 3/2 F – units, whereas, at higher x -values, fluoride tends to be sequestrated into amorphous domains rich in PbF 2 . In addition, both pulsed EPR studies of Yb 3+ doped glasses and photophysical studies of Eu 3+ doped samples indicate a mixed fluoride/borate coordination of the rare-earth ions and the absence of nanophase segregation effects.