Crystalline lanthanum-oxy-halide phosphor activated with rare earths

Abstract

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 1-y-z OX:Tm y 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.

Inventors

• 👤 Gerhard Herzog
• 👤 Detlef Starick
• 👤 Walter Tews
• 👤 Franz Braunholz
• 👤 Aleksander M. Gurvic
• 👤 Svetlana I. Golovkova
• 👤 Karl Dietzel

Bibliographic Details