Fabrication and characterization of porous glass derived optical materials and devices.
Item
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Title
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Fabrication and characterization of porous glass derived optical materials and devices.
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Identifier
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AAI9807923
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identifier
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9807923
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Creator
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Dong, Jinquan.
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Contributor
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Adviser: Harry D. Gafney
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Date
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1997
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Physical
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Abstract
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Previous studies in this laboratory have established that highly resolved patterns of refractive index gradients ranging from 0.01 to 0.001 can be produced by photolysis of iodotrimethylstannane adsorbed onto Corning's code 7930 porous Vycor glass (PVG) followed by thermal consolidation of the glass at 1200{dollar}\sp\circ{dollar}C. The goal of this work is to elucidate the photochemistry of the adsorbed precursor, the nature of the chemistry of the species in the matrix, and their effects on the host glass. (CH{dollar}\sb3)\sb3{dollar}SnI adsorbs onto the surface of PVG by forming a five coordinate complex with a surface silanol group. This interaction alters the nature of the Sn-I bond, which changes the course of the photochemical reaction. Under UV irradiation, in addition to the established homolytic cleavage of Sn-I bond found in hexane solution, the adsorbed precursor also undergoes heterolytic cleavage of Sn-I bond. The product of heterolytic cleavage chemically bonds to PVG surface and retains the pattern resolution during subsequent treatments. Thermal treatment removes the unreacted adsorbates and converts the photoproduct to transparent tin oxides. Deposition of tin oxides changes the density of the glass and in turn, its refractive index.;Photodeposited tin oxides also hinders the consolidation of PVG to nonporous glass. During thermal consolidation of PVG, photodeposited tin promotes the evaporation of boron from the glass matrix by competing with boron in glass network-forming ion position. The depletion of boron from porous glass surface increases the viscosity of the glass thereby changing its consolidation temperature relative to the bulk glass. Therefore, porous region can be patterned on a consolidated glass substrate by photopatterning tin oxides followed by appropriate heat treatments.;Electro-conductive indium tin oxide (ITO) coatings have been deposited on porous glass without a significant reduction in porosity or transparency of the substrate. Patterning conductive regions has been demonstrated by photopatterning a photoresist onto the ITO film and acid etching of the unprotected region, thus opening the door for the electro-optical applications of porous glasses.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
