Luminescence Properties of Thiogallate Phosphors: III . Red and White Emitting Phosphors for Flying Spot Scanner Applications

Abstract

Ions with the ns 2 electronic configuration were investigated as activators in the SrGa2S4 host lattice. Phosphors activated with Sn 2+ or Pb 2+ were found to cathodoluminesce in the red spectral region and exhibit relative efficiencies (~c ~ Rel.) of 1.1 and 4.6%, respectively. The Pb 2+ phosphor has a short fluores-cent decay time (Io/100 ~ 10-6 sec) and was found suitable for use as the red screen component in a flying spot scanner tube (FSST) employed as the transducer in color video playback. Coactivation of SrGa2S4 by Ce z + and Pb 2e was found to result in a white-emitt ing phosphor that exhibits lower noise in FSST screens than is usually found when phosphor blends are employed. The cathodoluminescence emission and decay prop-erties of the Ce 8 + activated alkaline earth thiogallates were reported earlier (1) with part icular emphasis on factors governing the use of these materials in flying spot cathode-ray tubes. Phosphors activated with ions possessing the ns 2 electronic onfiguration (T11+, Sn 2+, Pb 2+, Sb 3+, Bi 3+) are also of interest for use in this type of device because their fluorescence lifetime should be very short. As a consequence, these ions were also evaluated as activators in the SrGa2S4 host lattice, and this paper describes the cathodolumines-cence emission and decay characteristics of the Pb 2+ and Sn 2 + activated, and Ce 3 +-Pb 2 + coactivated SrGa2S4 phosphors and discusses their application in flying spot scanner tubes (FSST) designed for use in color video playback systems. Experimental Phosphor preparation.--The phosphors described herein were synthesized according to the general formulas