The luminescent properties and crystal structure of some new phosphor systems

New phosphor systems are described which illustrate the importance of combining the study of fluorescent properties of new systems with the results of X-ray analysis. The systems described include a range of tin-activated pro- and tetraphosphates of strontium and barium, and a group of manganese or cerium-manganese-activated silicates containing lithium. The preparation and fluorescent properties of these phosphors are discussed. X-ray methods have been used to identify the phases responsible for the various phosphors and a number of new phases including polymorphic forms, have been found. X-ray powder diffraction data are included. The practical importance of the new phosphors is discussed with reference to fluorescent lamps in general. Emphasis is placed on the colour correction of high pressure mercury vapour lamps by certain members of the complex lithium-containing silicate phosphors.