TY - JOUR

T1 - Structural response of a highly viscous aluminoborosilicate melt to isotropic and anisotropic compressions

AU - Wu, Jingshi

AU - Deubener, Joachim

AU - Stebbins, Jonathan F.

AU - Grygarova, Lenka

AU - Behrens, Harald

AU - Wondraczek, Lothar

AU - Yue, Yuanzheng

N1 - Funding Information: J.D. and L.G. thank the Deutsche Forschungsgemeinschaft (DFG) for financial support (Grant No. DE598/8-1). J.W. and J.F.S. acknowledge the support of the U.S. National Science Foundation, Grant No. DMR 0404972. L.W. thanks the DFG for further financial support under Grant No. WO1220/3-1. We thank N. Kim for assistance with XRD and D. Massiot (CNRS, Orléans, France) for making the “ DMFIT ” software freely available.

PY - 2009

Y1 - 2009

N2 - Aluminoborosilicate melts of E-glass composition have been compressed at pressures up to 500 MPa and subsequently cooled (4-5 K min-1) under pressure from well above the glass transition to room temperature. It is found that increasing uniaxial pressure lead to anisotropic glasses with increasing permanent birefringence, while increasing isostatic pressure resulted in isotropic glasses with increasing density (compaction of 2.1% at 500 MPa). Static and magic-angle spinning nuclear magnetic resonance spectroscopy of 11B, 23Na, 27Al, and 29Si were performed to explore pressure-induced changes in the short-range structure of these glasses. NMR experiments readily detected increasing IVB, VAl, and VIAl concentrations with pressure as well as a decrease in the mean distance of sodium to oxygen atoms (0.7% at 500 MPa), but no detectible evidence of short-range structural orientation around these atoms in the birefringent glasses were found. Quantifying the changes in the local boron, aluminum, silicon, and sodium environments revealed that the measured increase of recovered density with pressure in E-glass can only be partly explained by increase in B and Al coordination, and that overall compression of the network and of the network modifier cation volumes must also be important. Structural changes in the intermediate range, which were not detected by NMR, are discussed as a source of birefringence in anisotropic E-glass.

AB - Aluminoborosilicate melts of E-glass composition have been compressed at pressures up to 500 MPa and subsequently cooled (4-5 K min-1) under pressure from well above the glass transition to room temperature. It is found that increasing uniaxial pressure lead to anisotropic glasses with increasing permanent birefringence, while increasing isostatic pressure resulted in isotropic glasses with increasing density (compaction of 2.1% at 500 MPa). Static and magic-angle spinning nuclear magnetic resonance spectroscopy of 11B, 23Na, 27Al, and 29Si were performed to explore pressure-induced changes in the short-range structure of these glasses. NMR experiments readily detected increasing IVB, VAl, and VIAl concentrations with pressure as well as a decrease in the mean distance of sodium to oxygen atoms (0.7% at 500 MPa), but no detectible evidence of short-range structural orientation around these atoms in the birefringent glasses were found. Quantifying the changes in the local boron, aluminum, silicon, and sodium environments revealed that the measured increase of recovered density with pressure in E-glass can only be partly explained by increase in B and Al coordination, and that overall compression of the network and of the network modifier cation volumes must also be important. Structural changes in the intermediate range, which were not detected by NMR, are discussed as a source of birefringence in anisotropic E-glass.

UR - http://www.scopus.com/inward/record.url?scp=70349278626&partnerID=8YFLogxK

U2 - 10.1063/1.3223282

DO - 10.1063/1.3223282

M3 - Article

AN - SCOPUS:70349278626

VL - 131

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 10

M1 - 104504

ER -