LOW-PRESSURE MERCURY VAPOR DISCHARGE LAMP COMPRISING UV-A PHOSPHOR

摘要

The invention is concerned with a low-pressure mercury vapor discharge lamp comprising a light-transmitting discharge vessel, said discharge vessel enclosing, in a gastight manner, a discharge space provided with a filling of mercury, at least a part of wall of the discharge vessel being provided with a luminescent composition comprising a first UV-A phosphor of the general formula (Gdl-x-y-zYxLuy)P04:Cez, wherein 0 <= x < 1.0, 0 <= y < 1.0; 0 < z <= 0.2 and x + y + z < 1, the low-pressure mercury vapor discharge lamp comprising also discharge means for igniting and maintaining an electric discharge in the discharge vessel. Such a lamp is especially useful for tanning purposes as well as cosmetic and medical purposes. The invention is also concerned with an UV-A phosphor of the general formula (Gdl-x-y-zYxLuy)P04:Cez, wherein 0 <= x < 1.0, 0 <= y < 1.0; 0 < z <= 0.2 and x + y + z < 1.