Metallic Cluster Formation in Glasses
Date
2011-02
Authors
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Publisher
New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.
Abstract
Hydrogen reactions with glasses containing different metallic ions were
investigated. Hydrogen successfully reduced Ni, Co, Cu and Pb in soda-lime-silica
glasses at a range of different temperatures (500°C, 550°C, 600°C, and Tg). The
tarnishing model was successfully applied to account for the increase in the “free
hydroxyl” absorption band at high reaction temperatures. At lower temperatures, it was
shown that nickel and cobalt absorbance data did not follow the tarnishing model, most
likely due to the slow reaction rates involved with reducing these ions and a
dehydroxylation mechanism. The permeability of hydrogen molecules was calculated
from the absorbance data and found to be ~30 times lower than that reported in the
literature. This was again explained by a dehydroxylation mechanism. A possible
interaction between the metallic clusters and the glass matrix was identified for the lead
containing glass. This interaction is most likely an interfacial bond between the cluster
and the glass which results in a stretching of the lead lattice upon cooling.
Hydrogen also reduced indium in a series of sodium-indium-silicate glasses over a
range of temperatures (500°C, 550°C, 600°C, and Tg). The indium containing glasses all
exhibited an increase in the absorbance of the “free hydroxyl” band with the square root of
reduction time, but the trends with temperature were inconsistent. This was explained
through an enhanced dehydroxylation mechanism due to the high concentrations of
hydroxyl being formed in the glass. These glasses also exhibited a clear property change
(viscosity, Tg, durability, thermal expansion) at the surface due to the removal of indium
leaving residual soda-silicate glass in the composition region of immiscibility. Hydrogen
induced formation of alloys of nickel and copper was also demonstrated. The reaction rate
had little effect on alloy formation and as long as the metals in question will form an alloy
and diffuse at the treatment temperatures, an alloy composition is possible. This opens up
the door for a variety of new, unexplored, bulk properties for glasses ranging from
magnetism to catalysis.
Description
Advisory committee members: Alexis Clare, William Lacourse, S.K. Sundaram. Dissertation completed in partial fulfillment of the requirements for the degree of Doctorate of Philosophy in Glass Science at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University
Type
Thesis