%echnica Note p 9 2+ Cathodoluminescence of (Zn + Mg) ( OJ.Mn

Cathodoluminescent zinc-magnesium phosphate phos-phors activated by Mn 2+ are wel l-known (1-3). Zn ~ (PO4)2:Mn2+ had been used as red phosphor com-ponent in the early days of color television and is still available as P-27. The latter is reported to show, after excitation by short electron beam pulses, near-expo-nential afterglow requir ing approximately 27 msec to 1/10 of the original (4). We observed a substantial ly longer decay time, also near-exponential, in Mn-activated intermediate zinc-magnesium phosphate of the approximate composition ZnMgPO4.s. According to a published phase diagram (3), a chemical compound of this composition does not exist. A brief investiga-tion was initiated to determine the origin of the long decay time. The phosphors were prepared by standard tech-niques. The starting materials (ZnO, MgO, MnCO3, and HsPO4-solution) were mixed in aqueous slurries which were then dried and pulverized in a mortar. These powders were fired in open quartz containers in stag-nant air for one to several hours. The firing tempera-tures depended on the material and were in the 900 ~ 1150 ~ range. Emission spectra were measured under steady excitation by 8 kV electrons of low intensity (about 1 ~A/cm2). The spectra given in Fig. 1 are cor-rected for monochromator transmission and photomul-tiplier response. Efficiencies were compared, also under 8 kV excitation of low intensity, against NBS-1025 which is a Zn3 (PO4) 2:Mn 2+ phosphor eported to have an efficiency of about 6 % (5). Decay curves were de-, Electrochemical Society Active M mber. Key words: eathodoiuminescenee, luminescence., phosphor