Abstract: High-pressure discharge lamps generating UV radiation are provided with an internal safety switch, that interrupts the current circuit through the lamp upon fracture of the outer lamp envelope. In lamps according to the invention the safety switch is a member of a material selected from the group consisting of zirconium-aluminum alloys, sintered zirconium powder and sintered mixtures of zirconium powder and nickel powder.

Abstract: Composite body, a gas discharge lamp having a sodium pressure from 300-600 torr in particular, having an envelope of densely sintered aluminium oxide or of other sodium vapor-resistant materials and a feed-through member of tantalum, niobium or other metals equivalent thereto, the bonding material consisting of a finely dispersed polycrystalline product having a composition in mole % between the following limits:Al.sub.2 O.sub.3 --5-70at least one oxide chosen from Sc.sub.2 O.sub.3 and Ti.sub.2 O.sub.x, wherein2<.times.<4--2-70and at least one oxide chosen from:Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, Tb.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Ho.sub.2 O.sub.3, Er.sub.2 O.sub.3, Eu.sub.2 O.sub.3, Pr.sub.2 O.sub.3, Ce.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Tm.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Lu.sub.2 O.sub.3, La.sub.2 O.sub.3 and Nd.sub.2 O.sub.3 --10-80.

Abstract: An oxidation-sensitive element electrically connected in series with the discharge vessel of a high-pressure discharge lamp extinguishes the lamp when the element, upon fracture of the outer envelope of the lamp, is oxidized and prevents damage as a result of emission of UV radiation.In a high-pressure discharge lamp according to the invention, the oxidation-sensitive element (7) consists of an electric insulator (20) on which two spaced conductors (21, 22) are provided which are interconnected electrically by a vapor-deposited layer (23) of an oxygen-gettering metallic, evaporating getter. Opposite to the insulator (20) is present a holder (8) from which the getter was previously evaporated on to the insulator.