Erratum: “Observations on the Formation of Color Centers in Calcium Halophosphate” ]This Journal, 110, 374 (1963)lsqb;

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.

“…Strong absorption was found in the ultraviolet region which is in general agreement with that presented previously by Apple (7). After u.v.…”

Section: Esr Spectra Of Samples Containing Sb--esr Mea-supporting

confidence: 92%

Section: Optical Measurements On Crystals Containing Sb--supporting

confidence: 92%

Section: Depreciation Of Phosphorssupporting

confidence: 80%

“…Manuscript submitted Nov. 15,1974; revised manuscript received Feb. 7,1975. This was Paper 197 presented at the Toronto, Canada, Meeting of the Society, May 11-16, 1975.…”

mentioning

confidence: 99%

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

Warren

Ryan

Hopkins

et al. 1975

“…Depreciation under ultraviolet irradiation was accompanied by development of yellow body color due to color center formation (15,16) which decreased with M / P ratio (17). Depreciation of phosphors prior to E D T A washing (not shown) was severe and accompanied by black discoloration which increased with decreasing M / P ratio, i.e., opposite to the observed dependence of the yellow discoloration.…”

Section: Calciummentioning

confidence: 78%

Sb3+ and Mn2+ Activated Calcium Halophosphate Phosphors from Flux-Grown Apatites

Wachtel

1966

reduce the amounts of other impurities also if the oxychloride recrystallization process is used. It is evident that commercial sources of zirconia, if used in the preparation of other zirconium compounds, will introduce the same undesirable impurities if luminescence phenomena involving other activator ions are being considered, for example, the rare earths. It is possible that these impurities may not have as pronounced a detrimental effect in such compounds as they do in ZrO2 alone.It is probable that Ti 4+ replaces Zr 4+ in monoclinic ZrO2 substitutionally rather than interstitially. The usual coordination of Ti 4+ in oxide compounds is octahedral. In monoclinic ZrO2, however, the coordination of Ti 4+ is likely the same unusual asymmetric sevenfold coordination discussed previously. This highly asymmetric environment may account for the strong emission which can be developed.The slow build-up of steady-state luminescence and the long persistence of irradiated samples at room temperature is probably related to the filling and emptying of a relatively large number of traps which were shown to exist. Several strong g10w peaks were detected above liquid nitrogen temperature. One of the peaks occurs between 0 ~ and 20~ ABSTRACTThe crystallization of calcium chloro-and chloro-fluoroapatites from calcium halide fluxes was studied as a function of composition and heating schedules. Activation of Ca5 (PO4)3F0.9C10.1 was investigated by varying phosphor stoichiometry and firing methods. The results indicate that flux-grown apatites are slightly deficient in PO43-and that for a particle size of predominantly 50-100~, 72-hr firing at 1150~ causes only limited incorporation of Sb 3+, Cd 2+, and additional PO43-. The incorporation of Mn 2+ is more extensive and may be nearly uniform. The rate of migration of Mn and Sb toward the interior of the crystals increases with increasing PO48-[as (NH4)2HPO4] added prior to activation; however, maximum emission occurs at a calculated over-all metal/phosphorus ratio of exactly 5/3. High output of heterogeneously emitting crystals suggests that quantum efficiency is independent of activator concentration. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.102.42.98 Downloaded on 2015-03-13 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.102.42.98 Downloaded on 2015-03-13 to IP Vol. 113, No. 2 CALCIUM HALOPHOSPHATE PHOSPHORS ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.102.42.98 Downloaded on 2015-03-13 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.102.42.98 Downloaded on 2015-03-13 to IP

A Review of Depreciative Color Center Phenomena in Lamp Phosphors

Flaherty

1981

A review of the role played by color centers in the deterioration of lumen output of lamp phosphors with special attention to the halophosphates is presented. Color center dynamics in halophosphates result in a rapid degradation in phosphor brightness within minutes after the beginning of lamp life. An examination of the extent and rapidity of this effect is reviewed. Unirradiated spectral characteristics of halophosphates are dependent on growth stoichiometry. Radiatively induced spectral absorptions are dependent on the relative intensity of Hg u.v. components and crystal deformation and show thermal and optical bleaching effects. A dynamical model of color centers in halophosphates is extracted from the literature that explains the essential experimental dependencies. Related color center effects in phosphors including defect generation considerations for long‐term brightness deterioration are also presented.