The Deterioration of Blue Phosphor for Fluorescent Lamps

Tri-color type fluorescent lamps have been improved in their performance by various research efforts since the introduction to the market. In recent years, however, small size lamps have appeared and phosphors with superior resistance have been required under the severe conditions of these lamps. When compared with green phosphor and red phosphor, (Sr,Ba,Ca)10(PO4)6Cl2: Eu blue phosphor(SCA) is particularly easy to deteriorate. To investigate the causes of deterioration of SCA, we made serial experiments by the demountable discharge lamp apparatus (DDLA) and the fabrication of actual fluorescent lamps. It is noticed that ion bombardment and mercury absorption are related to the deterioration of SCA lamps. Surface coating is found to be effective to decrease the influence of both.