Transparent optical element - prodn from magnesia - alumina spinel an lithium fluoride by hot-pressure moulding

摘要

High temp-resistant optical element transparent in visible and infra-red wave ranges of electromagnetic spectrum, useful as casing-windows for ionised alkali vapour lamps, is produced by heating material of 1 mu particle size, contg. equimolar amounts of MgO and Al203 and evenly mixed with 0.2-4, pref. 2, wt.% powdered LiF, in vacuo to 800-1250 degrees C, and then exerting a pressure of =980, pref. 1050, kg/cm2 on material for 30-60 min. after its temp. has been raised to 1300-1600 degrees C.