Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Patent
1998-07-20
1999-09-14
Koslow, C. Melissa
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
2523016F, C09K 1159, C09K 1166
Patent
active
059519150
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an europium-activated silicate type phosphorescent phosphor which is excellent in weather resistance, has a long afterglow characteristic and exhibits blue to green emission under excitation with ultraviolet rays and/or visible light rays, and which is useful as a light source or a display in a dark place such as indoor or outdoor or in water.
BACKGROUND ART
A phosphorescent phosphor is a phosphor which continues to emit fluorescence even after termination of excitation after some excitation is imparted to the phosphor to emit fluorescence. For a phosphorescent phosphor, along with diversification and high functionalization of display, multi-coloring, long afterglow and improved weather resistance of a phosphorescent phosphor are desired. With conventional phosphorescent phosphors, the types of colors of the fluorescence and afterglow were limited, the weather resistance was poor, and the afterglow time was short.
As a blue-emitting phosphorescent phosphor, a (Ca,Sr)S:Bi phosphor is known. As a yellowish green-emitting phosphorescent phosphor, a ZnS:Cu phosphor is known, and as a red-emitting phosphorescent phosphor, a (Zn,Cd)S:Cu phosphor is known.
However, the above-mentioned (Ca,Sr)S:Bi phosphor is not practically used at present, since the chemical stability of the host material is extremely poor, and the luminance and afterglow characteristics are inadequate. On the other hand, the (Zn,Cd)S:Cu phosphor is not practically used at present, since Cd which is a toxic substance, occupies almost a half of the host material, and the luminance and afterglow characteristics are not satisfactory. ZnS:Cu is also susceptible to decomposition by ultraviolet rays in the presence of moisture and is likely to be blackened, and the afterglow characteristics are also unsatisfactory, but it is inexpensive and is used mostly for face plates of clocks or for indoor use such as emergency escape signs.
DISCLOSURE OF THE INVENTION
The present invention is to overcome the above drawbacks and to provide a phosphorescent phosphor which has a long afterglow characteristic and blue to green emission and which is further chemically stable and excellent in weather resistance.
Namely, the present invention is a phosphorescent phosphor which has the following construction and which exhibits blue to green emission.
(1) In an Eu-activated silicate phosphorescent phosphor, a phosphorescent phosphor represented by a compositional formula m(Sr.sub.1-a M.sup.1.sub.a)O.n(Mg.sub.1-b M.sup.2.sub.b)O.2(Si.sub.1-c Ge.sub.c)O.sub.2 : Eu.sub.x Ln.sub.y, wherein M.sup.1 is at least one element selected from Ca and Ba, M.sup.2 is at least one element selected from Be, Zn and Cd, and the coactivator Ln is at least one element selected from Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, B, Al, Ga, In, Tl, Sb, Bi, As, P, Sn, Pb, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Cr and Mn, and wherein a, b, c, m, n, x and y are within the following ranges, and said phosphor contains at least one halogen element selected from F, Cl, Br and I in an amount within a range of from 1.times.10.sup.-5 to 1.times.10.sup.-1 g.multidot.atm/mol of the host material:
(2) The phosphorescent phosphor according to the above (1), wherein the above value m satisfies a condition represented by 1.7.ltoreq.m.ltoreq.3.3.
(3) The phosphorescent phosphor according to the above (1) or (2), wherein the above coactivator Ln is at least one element selected from Dy, Nd, Tm, Sn, In and Bi.
(4) The fluorescent phosphor according to any one of the above (1) to (3), which exhibits thermoluminescence at a temperature of at least room temperature, when heated after excitation with ultraviolet rays and/or visible light rays within a range of from 140 to 450 nm.
The present inventors have conducted a study primarily on a phosphor host material of (Sr,M.sup.1)O--(Mg,M.sup.2) O--(Si,Ge)O.sub.2 type (M.sup.1 =at least one of Ca and Ba, and M.sup.2 =at least one of Be, Zn and Cd), whereby they have found that a phosphor host material suitable f
REFERENCES:
patent: 3544482 (1970-12-01), Barry
patent: 3676361 (1972-07-01), Datta
patent: 5231328 (1993-07-01), Hisamune et al.
patent: 5839718 (1998-11-01), Hase et al.
Chem. Abstract citation for JP 9-194,833, Jul. 29, 1997.
Hase Takashi
Hayakawa Morio
Kotera Noboru
Miura Norio
Sakamoto Hitoshi
Kasei Optonix Ltd.
Koslow C. Melissa
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