title: 27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy of glasses in the system K2O-Al2O3-SiO2.
abstract: 27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy at 78 MHz has been applied to determine (true) chemical shift and quadrupole coupling parameters of glasses in the system K2O-Al2O3-SiO2 with 60-80 mol% SiO2 and K2O concentrations between 0 and 24 mol%. The powdered crystalline aluminosilicates andalusite and sillimanite have also been examined. In the glasses, all Al appears to be tetrahedrally bound in the aluminosilicate network unless x = mol% K2O:mol% Al2O3 becomes extremely small. Upon decreasing x the distortion of the tetrahedral Al(OSi)4 units increases in steps, and possible explanations are discussed. Six-coordinated aluminum observed for x < 0.2 is connected with the occurrence of interstitial Al3+ ions which charge-compensate the AlO4 units in addition to K+.
authors: Institute für Physikalische Chemie, Westfälische Wilhelms-Universität, Münster, Germany.
authors: C
authors: C
authors: Mundus
authors: W
authors: W
authors: Müller-Warmuth
mesh_terms: D000535:Aluminum; D000537:Aluminum Oxide / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010087:Oxides / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D010087:Oxides; D017680:Potassium Compounds; C068440:potassium oxide; D012822:Silicon Dioxide; D000535:Aluminum; D000537:Aluminum Oxide