Abstract: A glass composition for a seal consists essentially of 70-75 wt % of PbO, 3-7 wt % of PbF2, 5-8 wt % of Bi2O3, 5-7 wt % of B203, 2-5 wt % of ZnO, 1-3 wt % of Fe2O3, 0-2 wt % of CuO, 0-2% of TeO2, and a trace <0.2% of MnO2, the composition having a flow temperature of <350° C. Such seals can be flowed at low temperatures, using different and less environmentally damaging constituents to those used before. Damage to temperature sensitive materials near the seals, can be reduced. Low flow temperatures can be achieved without excessive degradation of properties such as low viscosity, low expansion coefficient, good adhesion to glass and metals, low permeability of air, good long term hydrolytic stability. A filler such as a ceramic powder, is added to match the temperature expansion coefficient to the materials being sealed. It can be used to fix silica fiber into electro-optic devices to achieve hermetic joints with high mechanical stability.

Abstract: A glass composition for a seal consists essentially of 70-75 wt % of PbO, 3-7 wt % of PbF2, 5-8 wt % of Bi2O3, 5-7 wt % of B203, 2-5 wt % of ZnO, 1-3 wt % of Fe2O3, 0-2 wt % of CuO, 0-2% of TeO2, and a trace <0.2% of MnO2, the composition having a flow temperature of <350° C. Such seals can be flowed at low temperatures, using different and less environmentally damaging constituents to those used before. Damage to temperature sensitive materials near the seals, can be reduced. Low flow temperatures can be achieved without excessive degradation of properties such as low viscosity, low expansion coefficient, good adhesion to glass and metals, low permeability of air, good long term hydrolytic stability. A filler such as a ceramic powder, is added to match the temperature expansion coefficient to the materials being sealed. It can be used to fix silica fiber into electro-optic devices to achieve hermetic joints with high mechanical stability.