title: Structural changes above the glass transition and crystallization in aluminophosphate glasses: an in situ high-temperature MAS NMR study.
abstract: We present an in situ high-temperature nuclear magnetic resonance study on the structural changes in aluminophosphate glasses occurring in the temperature range between the glass transition temperature Tg and the crystallization temperature Tc, Tg < T < Tc. Decisive changes in the network organization between Tg and Tc in potassium aluminophosphate glasses in the compositional range 50K2O-xAl2O3-(50 - x)P2O5 with 2.5 < x < 20 could be monitored for the first time employing 1D 31P- and 27Al-MAS NMR. Accompanying ex situ NMR experiments (31P-RFDR NMR and 31P-{27Al} CP-HETCOR NMR) on devitrified samples were performed at room temperature to further characterize the phases formed during the crystallization process. The structural role of boron-which is known to inhibit the crystallization process in these aluminophosphate glasses-on short and intermediate length scales was analyzed employing 11B-MQMAS, 11B-{27Al} TRAPDOR and 11B-{31P} REDOR NMR spectroscopy.
authors.affiliation: Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30-36, D-48149 Münster, Germany.
authors.forename: Leo
authors.initials: L
authors.lastname: van Wüllen
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wegner
authors.forename: Gregory
authors.initials: G
authors.lastname: Tricot
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D003460:Crystallization; D005898:Glass / Q000737:chemistry*; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D010710:Phosphates / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D010710:Phosphates; C012714:aluminum phosphate