| 摘要 |
A glass, capable of transmitting electro-magnetic radiations of a wavelength of 6.5 microns and above and having a softening point above 300 DEG C. and preferably above 650 DEG C., contains by weight 0.66 to 1.13 parts of gallium oxide to 1 part of strontium oxide and these oxides constitute at least 50% by weight of the glass. There may also be present up to 45% by weight of lead oxide, up to 35% of one or more of the oxides of lithium, sodium, potassium, calcium, and magnesium, and up to 40% of the oxides of one or more of copper, zinc, cadmium, lanthanum, titanium, zirconium, thorium, germanium, tantalum, arsenic, and antimony. The oxides may be employed in the form of salts which on heating yield the oxides, or they may be replaced by the corresponding molar percentages of the fluorides. The ingredients are fused together at a temperature in excess of 1400 DEG C.
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