Abstract: The electric lamp comprises a lamp vessel (1) which is transparent to visible light and which accommodates a light source. At least a part of the lamp vessel (1) is covered with a light-absorbing coating (3). According to the invention, the light-absorbing coating (3) comprises a network which can be obtained by conversion of an organically modified silane by a sol-gel process. The organically modified silane is selected from the group formed by compounds of structural formula R′Si(OR″)3, wherein R′ is an alkyl or aryl group and R″ is an alkyl group. Preferably, R′ is CH3 or C6H5 and R″ is CH3 or C2H5. Nano-sized silica particles having a diameter d≦50 nm may be incorporated in the network. The pigment is preferably chosen from the group formed by Fe2O3, P-doped Fe2O3, ZnFe2O4, ZnO.Fe2O4, CoAl2O4, Nd2O5, BiVO4 and zirconium praseodymium silicate or mixtures thereof.

Abstract: The present invention relates to an improved maintenance, low-pressure mercury vapor discharge lamp having a discharge vessel enclosing a discharge space provided with a filling of mercury and a rare gas in a gastight manner. The discharge vessel is made from a glass of essentially 60-80% by weight SiO2 and 10-20% by weight Na2O. Preferably, the composition of this so-called sodium-rich glass is made of 70-75% by weight SiO2, 15-18% by weight Na2O and 0.25-2% by weight K2O. At least a part of the inner surface of the discharge vessel is provided with a transparent layer having a borate or a phosphate of an alkaline-earth metal and/or of scandium, yttrium or another rare earth metal. Preferably, the alkaline-earth metal is calcium, strontium and/or barium. In a particularly preferred embodiment, the transparent layer is made of yttrium borate and strontium borate. Additionally, the transparent layer preferably has a thickness between 5 and 200 nm and has provided on it a luminescent layer.

Abstract: A low-pressure mercury vapor discharge lamp is provided with a discharge vessel (10). The discharge vessel (10) encloses a discharge space (11) provided with a filling of mercury and a rare gas in a gastight manner. According to the invention, the discharge vessel is made from a glass comprising silicon oxide and sodium oxide in the following percentages by weight: SiO2 60-80 wt. % and Na2O 10-20 wt. %. Preferably, the glass composition comprises SiO2 70-75 wt. %, Na2O 15-18 wt. % and K2O 0.25-2 wt. %, so that this glass is a so-called sodium-rich glass as compared to the customarily used mixed alkali glass. At least a part of an inner surface of the discharge vessel (10) is provided with a transparent layer (16) comprising a borate or a phosphate of an alkaline-earth metal and/or of scandium, yttrium or another rare earth metal. Preferably, the alkaline-earth metal is calcium, strontium and/or barium. Preferably, the transparent layer (16) comprises yttrium borate and strontium borate.