ELECTRON-SPECTROSCOPY FOR CHEMICAL-ANALYSIS OF COOL WHITE PHOSPHORS COATED WITH SIO2 THIN-FILM

Silica formed on the surface of Cool White phosphor by precipitation o f either tetraethylorthosilicate or Ludox AM (aqueous colloidal silica ) is not homogenously distributed. Electron spectroscopy for chemical analysis indicates that oxygen sites of the phosphor surface are prefe rentially coated. The preference for oxygen sites is likely the result of hydrogen bonding formation available at these sites. There was no preference for the remaining sites (Ca, F, and P) which are probably a dsorbed by physisorption.