Abstract
The distribution of bridging and non-bridging oxygens is a fundamental aspect of the intermediate range order of silicate glasses and liquids. Disorder in this distribution can be characterized by the relative abundances of Qn species, which can be quantified by 29Si NMR on both spinning and static samples. We emphasize the latter here, and show that increasing the field strength of the network modifying cation and increasing temperature have similar randomizing effects on this distribution. These changes have a major influence on thermodynamic activities. In the liquid, exchange between sites is rapid, but the exchange rate may become slow enough with decreasing temperature to actually define Tg. In silicate liquids, some kind of high energy, low abundance, defects probably are present to allow this structural change to occur, to account for the bulk of the configurational heat capacity, and to explain the observed spin-lattice relaxation times.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
