Electrically Conducting Glass Fibers

Fiber formation and electrical conductivity were investigated in molybdenum phosphate glasses containing Ag₂O; PdO was substituted for Ag₂O and other constituents in the base glass. Temperature coefficients of electrical resistivity and linear expansion and other properties were determined for the bulk glasses. X-ray diffraction confirmed that some compositions were amorphous; these glasses could be drawn by conventional methods into continuous filaments. Migration and reduction of Ag⁺ at the glass fiber surfaces, induced by a secondary heat treatment, formed a metallic, electrically conducting, solder-able surface film. Filament resistance of 0.07 Ω/ft/2000 fibers was achieved; resistance increased nearly linearly with temperature from −200° to 200°C. Imperfections in the metallic film, acting as flaw sites, contributed to a reduction of ∼50% in tensile strength compared to that of pristine fibers.