Reactions Between Liquid Metal Alloys and Doped (Semiconducting) Aluminosilicate Glassmelts

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Abstract - Cooper - 0071325The foundation for the research planned are discoveries in the PI's group that resulted in a predictive dynamic reaction model for the float-glass process. In "traditional" float glass (flat glass prepared from floating a soda-lime silicate melt on pure molten tin, highest temperature of ~1100oC), the large driving-force (energy) of reaction is dissipated most rapidly by a redox dynamic that is dominated by the diffusive motions of electron holes and network-modifying cations. The PI's model explains many idiosyncratic features of the chemical profile in float glass. Combined with solution thermodynamics for float-alloy design, the model was used to extrapolate the float-glass process to temperatures in excess of 1400oC, opening the possibility of float-processing flat glass of distinctly refractory compositions (e.g., for application as substrates in high-end flat-panel displays). The model also suggests a framework of understanding in which glass composition and float-medium composition can be engineered together so as to create high-value-added flat glass with unique physiochemical properties and performance. The research planned represents the first steps to "designer"-flat-glass of unique properties.The PI plans to conduct an experimental and theoretical study of the reaction(s) between molten aluminosilicate solutions with molten metal solutions, specifically:(1) the driving force and chemical species involved in the redox couple at the silicate-metal interface,(2) the physical mechanism(s) of chemical diffusion in the reacting aluminosilicate glassmelt in response to the chemical diffusion accompanying the overall reaction.In addition, the physical properties/characteristics of the reacted glassmelt via its reaction with the liquid metal alloy allows for creation of a surface with perhaps unique catalytic, photonic or thermochemical (e.g., crystalline nucleation) responses.Specifically, there will be two experimental thrusts: (a) time/temperature/distance (i.e., into the glassmelt) analyses of reactions between Cu-37Ge (at.%) and both iron-free and ferric-iron-doped sodium aluminoborosilicate (NABS which is similar to Pyrex) and magnesium aluminosilicate glassmelts, and (b) structural and chemical (radial distribution function and electron loss spectroscopy) analyses of reacted glassmelts as functions of chemical-diffusion-affected composition, at an anticipated lateral resolution of 5-10 nm, using energy-filtered transmission electron microscopy.This project is being co-funded by the Ceramics Program in the Division of Materials Research (Mathematical and Physical Sciences Directorate) and the Process and Reaction Engineering Program in the Division of Chemical and Transport Systems (Engineering Directorate).