The Interaction of Color Centers and Cd+2 and Sb+3 Ions in Calcium Fluorophosphate

Abstract

Calcium fluorophosphate powders containing various amounts of cadmium and antimony and single crystals containing antimony were subjected to u.v. irradiation and thermal annealing treatments. The color centers formed by the irradiations were studied by electron spin resonance and by optical techniques. Two previously unreported color centers were observed, one associated with the presence of antimony and the other with the presence of cadmium. Growth dynamics and models for these two centers are given and their importance in phosphors is discussed. A simple model for phosphor depreciation is proposed in which these centers play crucial roles.* Electrochemical Society Active Member.

A Review of Depreciative Color Center Phenomena in Lamp Phosphors

“…The absorption spectrum [from Ref. (30)] of Sb in a single crystal of fluorophosphate is presented in Fig. 8.…”

“…irradiation induces many absorptions throughout the visible and u.v. as well as a variety of ESR spectra (6,12,16,29,30,(32)(33)(34) in the halophosphates. This coloration occurs in fluoro, chloro, and all proportions of chlorofluorophosphates with only unessential variations in the shapes and peak positions of the induced absorption bands and are therefore associated with defects or color centers common to the halophosphate structure.…”

“…The absorptions are labeled according to Ref. (29,30). The top of the figure presents regions of absorption in the unactivated and unirradiated halophosphate.…”

“…These absorptions are taken from Ref. (12,14,29,30,32). They were induced by high energy irradiations from 185 nm of Hg, x-rays, and those associated with the tesla coil.…”

“…In addition to the spectral evaluation of these absorption bands induced by high u.v. irradiation, extensive electron spin resonance (ESR) investigations were performed (16,26,29,30,32,35). There occurred a good amount of ESR spectra that was induced by high u.v.…”