Crystalline lanthanum-oxy-halide phosphor activated with rare ea

Details Crystalline lanthanum-oxy-halide phosphor activated with rare ea Crystalline lanthanum-oxy-halide phosphor activated with rare ea

1987-09-30

1988-12-27

Cooper, Jack

Compositions

Inorganic luminescent compositions

Compositions containing halogen; e.g., halides and oxyhalides

C09K 1186

Patent

active

047939443

ABSTRACT:
The invention concerns a crystalline lanthanum-oxy-halide phosphor activated with rare earths which emits light in the ultraviolet and blue spectral range by high-energy excitation, particularly X-ray excitation. Such phosphors are used, for instance, in X-ray image converters, particularly in X-ray amplifying screens. It is the object and purpose of the invention to state a new oxy-halide phosphor with changed composition which ensures a high image quality of corresponding amplifying screens and at sufficiently little phosphorescence renders an optimal conversion of the X-rays to the photographically effectual luminescence possible. This is achieved by simultaneous use of thulium and gadolinium as activators where the phosphor represents the general formula La.sub.1-y-z OX:Tm.sub.y.sup.3+, in which X=Cl and/or Br and y represents values from 0.0001 to 0.1 preferably from 0.0005 to 0.005 as well as z represents values from 0.001 to 0.3 preferably from 0.002 to 0.05. These phosphors can be manufactured in a simple manner, for instance, by converting a mixed oxide of lanthanum, thulium and gadolinium with a suitable ammonium halide, followed by a recrystallization of the resulting materials and adding fluxes. The emission spectrum of such phosphor is illustrated in FIG. 1.

REFERENCES:
patent: 3795814 (1975-03-01), Rabatin
patent: 4246485 (1981-01-01), Bossomaier et al.
patent: 4315979 (1982-02-01), Brines et al.
patent: 4316092 (1982-02-01), Rabatin
patent: 4360571 (1982-11-01), Rabatin
patent: 4478933 (1984-10-01), Rabatin
patent: 4499159 (1985-02-01), Brines et al.
patent: 4532070 (1985-07-01), Rabatin
patent: 4578211 (1986-03-01), Rabatin

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