Effect of temperature on the degradation of ZnS FED phosphors

Abstract

AbstractThe changes in cathodoluminescent brightness and changes in the surface chemistry of ZnS:Cu,Al,Au have been investigated using Auger electron spectroscopy (AES) and a photospectrometer. The ZnS:Cu,Al,Au phosphor powders have been subjected to electron beam bombardment of 2 keV, with an electron beam current density of 88 mA cm−2 at an oxygen pressure of 2 × 10−6 Torr. The studies were carried out between room temperature and 310 °C. Degradation was manifested by a non‐luminescent ZnO layer that formed on the surface of the phosphor according to the electron‐stimulated surface chemical reaction (ESSCR) mechanism. An increase in temperature led to a decrease in the surface reaction rate due to a decrease in the mean surface lifetime of the oxygen molecules on the surface, with a direct decrease in the ESSCR probability. Without the presence of the electron beam, no chemical reactions occurred on the surface up to 310 °C. Local heating due to the electron beam irradiation is not responsible for the chemical reactions on the ZnS phosphor surface. Copyright © 2001 John Wiley & Sons, Ltd.