Zur Aluminiumkoordination in Alumoboratgläsern

Atomic structure of beryllium boroaluminate glasses: A multi-nuclear NMR spectroscopic study

“…Samples were synthesized from reagent grade BeCO 3 , H 3 BO 3 and Al(OH) 3 . The batch materials were mixed in stoichiometric proportions, decarbonated, dehydrated and melted in 20-30 g batches in platinum crucibles at 1400-1500°C for 1 h. Melts were poured into steel molds and resulting glasses were annealed at temperatures near the respective T g s.…”

“…The atomic structures of these glasses have been studied in detail primarily with 11 B and 27 Al and more recently with 17 O nuclear magnetic resonance (NMR) spectroscopic techniques and been found to be characterized by an unusually wide variety of nearest-neighbor Al-O and B-O coordination environments [3][4][5][6][7][8][9][10][11][12][13]. For example, B atoms in trigonal and tetrahedral coordination with oxygen (denoted here as B III and B IV , respectively) and Al atoms that are 4, 5 and 6-coordinated to oxygen (denoted here as Al IV , Al V and Al VI , respectively) can coexist in the same glass structure.…”