Properties of fast-decay cathode-ray tube phosphors

Cathodoluminescent efficiency, decay time, aging characteristics, spectral distribution, and temperature dependence of luminescent emission have been measured for the more intense fast-decay phosphors. Materials studied were ZnS(Ag, Ni); ZnO(Zn) = P24; BaPbSO4; (CaO)2·MgO·(SiO2)2·(Ce) = P16; and CaO·Al2O3·(SiO)2·(Ce) = P16. The intensities of the P16 and P24 samples were observed, to a good approximation, to be proportional to the decay times. Aging due to electron bombardment was found to be fastest for BaPbSO4 and the P16 CaMg-silicate, slower for the P16 CaAl-silicate, and slowest for P24 and ZnS-(Ag, Ni). The decay was nonexponential for all the phosphors studied and the decay time became shorter with increasing beam current density. The intensity generally decreased with temperature, reaching 10 per cent of the room temperature value at about 200°C, 300°C, 350°C, 600°C, for the ZnS(Ag, Ni), BaPbSO4, P24, and CaAl-silicate, respectively. The CaMg-silicate retains 90 per cent of its 20°C intensity at a temperature of 600°C. Investigations were also conducted on optimum screen weight, effects of particle size distribution, and on screen preparation techniques, all of which will be discussed. It is concluded that phosphor characteristics differ significantly between batches and manufacturers. A detailed evaluation of the important parameters should be conducted on individual phosphor batches for applications where screen characteristics are critical.