Stoichiometry of Luminescent Apatites

Lutetium oxychloride and oxybromide phosphors have been prepared using Tb3+, Tm3+, Ce3+, Sm3+, and Dy3+activators. In general, luminescent characteristics are similar to those found for corresponding lanthanum oxyhalide phosphors. The stability of lutetium oxyhalides is markedly decreased apparently due to the effect of the lanthanide contraction phenomenon. Apparently for the same reason, emissions from the Tm3+ 3P0 excited states occur about 10 nm lower than those for corresponding lanthanum oxyhalide phosphor emissions. Tb3+, Tm3+, and Ce3+ activated phosphors are efficient under x‐ray excitation and may have use in image intensifiers for high kilovolt peak applications in medical radiography. Emissions from the Tm3+ 3P0 have a broad‐band character similiar to that found in normalLaOBr:normalTm phosphors.

Section: Methodsmentioning

confidence: 99%

Luminescence of Rare Earth Activated Lutetium Oxyhalide Phosphors

Rabatin

1982

“…Its s 2 configuration, leaving it nonparamagnetic, makes it uncertain as to its occupation position. By charge compensation arguments (20) it is assumed to occupy the Ca (II) site with an oxygen substituting for the neighboring fluorine ion. Dale (21) has some experimental evidence suggesting the substitution of Sb for phosphorus.…”

Section: General Lumen Dependenciesmentioning

confidence: 99%

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.

“…Strong evidence suggests that antimony ions enter the apatite structure as antimony-oxygen pairs, with the oxygen located on a halogen site and the antimony on one of the three adjacent Ca(II) positions (1)(2)(3). We conclude that the Mn(Sb) center consists of a manganese ion located on a Ca(II) site adjacent to a antimony-oxygen complex.…”

Section: Discussionmentioning

confidence: 87%

“…A CW phosphor may be viewed as being calcium fluorophosphate with about 10% of the fluorine ions replaced by chlorine, 2% of the calcium ions by manganese, and an additional 1% by cadmium. Antimony is believed to be incorporated as an antimony-oxygen pair replacing a calcium(II) ion and its adjoining fluorine ion (1)(2)(3). If this model is correct, an additional ~/~ % of the calcium ions are replaced with antimony and an additional 2 ~ % of the fluorine ions by oxygen.…”

mentioning

confidence: 99%

The Optical Properties of Mn+2 in Calcium Halophosphate Phosphors

Ryan¹,

Vodoklys²

1971

A study of the optical properties of Mn+2 in commercial halophosphate phosphors has revealed that the Mn+2 is located on four distinguishable sites: on the simple Ca(I) site, on the simple Ca(II) site, on a Ca(II) site adjacent to an antimony‐oxygen pair, and on a Ca(II) site adjacent to a chlorine ion in those phosphors containing chlorine. The Mn+2 fluorescence that results when the excitation is via energy transfer from antimony ions is primarily due to Mn+2 situated on a Ca(I) site, with smaller components due to Mn+2 located on the other sites observed.