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.
The pink coloration often found in calcium halophosphate phosphors has been found to be associated with the presence of an impurity phase of ~(Ca, Mn)3(P04)2 which forms on partial degradation of the phosphor. The identification, preparation, properties, and mode of formation of this impurity are described. The pink coloration is due to trace amounts of Mn +3. Because Mn +3 absorbs strongly in both the visible and ultraviolet regions, it has a deleterious effect on phosphor brightness. * Initial chloride content 0.62 w/o. ** Chloride loss limited due to the low amount of Ca~P207 initially present.
LiGaO2: Fe is an efficient phosphor under both ultraviolet and cathode-ray excitations, with peak emission at 742 nm in the near-infrared region. It is best prepared at about 1000~ with stoichiometric proportions of the host ingredients and 0.01 moles Fe2Os. At this optimum Fe 3+ concentration, the relative quantum efficiency is about 80%. Potential use in fluorescent lamps is discussed in relation to plant growth applications ~or activation of the enzyme phytochrome.The behavior of Fe 3 + ions in various hosts has been studied extensively. In LiA15Os with a spinel-like structure (1), Fe 8+ activator has a peak emission at about 680 nm under 254 nm excitation (2). On the other hand, Fe3+-activated LiA102 with a distorted tetragonal structure (3) emits at about 740 nm (4). In the search for efficient near-infrared emitting phosphors for special fluorescent lamp applications, the author examined several gallium-containing hosts for possible emission when activated with iron. LiGaO2: Fe was found to be an efficient phosphor under both ultraviolet (u.v.) and cathode-ray (CR) excitation. This paper describes the preparation, luminescent properties, and performance of LiGaO2:Fe in fluorescent lamps. Comparisons with LiA102:Fe phosphors are also described. Some potential uses in fluorescent lamp applications are indicated.
Total chemical analysis of luminescent apatite together with quantitative x-ray diffraction analysis for secondary phases have made it possible to delineate the maximum permissible nonstoichiometry. Based on the accuracy of the various methods and expressed as a deficiency of calcium, the extent of nonstoichiometry is less than the absence of one calcium in every 380 calcium sites. Quantitative experimental evidence is also presented to support the hypothesis for charge compensation of antimony by a corresponding oxygen substitution at halogen sites.
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