title: Oxygen-17 nuclear magnetic resonance study of the structure of mixed cation calcium-sodium silicate glasses at high pressure: implications for molecular link to element partitioning between silicate liquids and crystals.
abstract: The structure of silicate glasses and the corresponding liquids at high pressure and their structure-property relations remain difficult questions in modern physical chemistry, geochemistry, and condensed matter physics. Here we report high- resolution solid-state O-17 3QMAS NMR spectra for mixed cation Ca-Na silicate glasses quenched from melts at high pressure up to 8 GPa. The spectra provide the experimental evidence for the varying pressure-dependence in two different types of nonbridging oxygen (NBO) environments (i.e., Na-O-Si and mixed (Ca,Na)-O-Si) in the single glass composition. The percentage of NBO drops significantly with increasing pressure and is a complex function of melt composition, including cation field strength of network modifying cations. A decrease in NBO fraction with pressure is negatively correlated with the element partitioning coefficient between crystals and liquids at high pressure.
authors: School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea. sungklee@snu.ac.kr
authors: Sung Keun
authors: SK
authors: Lee
authors: George D
authors: GD
authors: Cody
authors: Yingwei
authors: Y
authors: Fei
authors: Bjorn O
authors: BO
authors: Mysen