Degradation of Y 2SiO 5:Ce phosphor powders

Abstract

The degradation of the cathodoluminescence (CL) intensity of cerium-doped yttrium silicate (Y 2SiO 5:Ce) phosphor powders was investigated for possible application in low voltage field emission displays (FEDs). Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and CL spectroscopy were used to monitor changes in the surface chemical composition and luminous efficiency of commercially available Y 2SiO 5:Ce phosphor powders. The degradation of the CL intensity for the powders is consistent with a well-known electron-stimulated surface chemical reaction (ESSCR) model. It was shown with XPS and CL that the electron stimulated reaction led to the formation of a luminescent silicon dioxide (SiO 2) layer on the surface of the Y 2SiO 5:Ce phosphor powder. XPS also indicated that the Ce concentration in the surface layer increased during the degradation process and the formation of CeO 2 and CeH 3 were also part of the degradation process. The CL intensity first decreased until about 300 C cm −2 and then increased due to an extra peak arising at a wavelength of 650 nm.