| abstract |
A low pressure mercury vapor discharge lamp is provided, said discharge lamp ( 10 ) comprising an envelope ( 12 ) formed from light-transmitting material and containing an ionizable gas fill ( 22 ), mercury, and electrodes ( 18 ) sealed in the envelope. The envelope ( 12 ) is provided with a single layer coating ( 14 ) on the internal surface thereof next to the discharge space. The coating ( 14 ) contains halo-phosphate phosphor and 5-30 mass % aluminum oxide relative to the halo-phosphate phosphor, and the primary particle size of the aluminum oxide is smaller than 30 nanometers, the floc size of the aluminum oxide is smaller than 1 micrometer, and the void fraction of the total floc volume is at least 50%. |