Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Reexamination Certificate
2001-09-10
2004-08-10
Koslow, C. Melissa (Department: 1755)
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
Reexamination Certificate
active
06773629
ABSTRACT:
The present invention relates to a compound based on an alkaline-earth metal, sulphur and aluminium, gallium or indium, its method of preparation and its use as a phosphor.
At the present time there have been major developments in the fields of luminescence and electronics. As an example of such developments, mention may be made of the development of cathodoluminescent systems for new display and illumination techniques. A specific application is that of the replacement of current television screens with flat screens. These new applications require phosphors having increasingly improved properties.
Known phosphors include, in particular, alkaline-earth metal thiogallates. These products may especially be prepared by spray-drying a solution or suspension of the constituent elements of the thiogallate other than sulphur, and then by sulphurizing the spray-dried product. The products obtained in this way already have good luminescence properties.
It is an object of the invention to further improve these properties.
To this end, the compound of the invention is a compound based on at least one element A chosen from alkaline-earth metals, on at least one element B chosen from aluminium, gallium and indium, on sulphur and on a dopant capable of giving the said compound luminescence properties, and it is characterized in that it is in the form of a mixture of predominantly an AB
2
S
4
-type crystallographic phase and a B
2
S
3
-type crystallographic phase.
The invention also relates to a method of preparing such a compound, which is characterized in that it comprises the following steps:
a solution or suspension containing salts or sols of the elements A, B and of the dopant is formed, in a proportion such that the B/(A+dopant) atomic ratio is at least 2.06;
the solution or suspension is spray-dried; and
the product obtained in the previous step is sulphurized.
Finally, the invention relates to the use as a phosphor, especially in cathodoluminescence, of a compound as described above.
Further features, details and advantages of the invention will become more fully apparent on reading the description which follows and from the appended drawing in which:
REFERENCES:
patent: 5505986 (1996-04-01), Velthaus et al.
patent: 5747929 (1998-05-01), Kato et al.
patent: 5773085 (1998-06-01), Inoue et al.
patent: 6180073 (2001-01-01), Huguenin et al.
patent: 2002/0149001 (2002-10-01), Ellens et al.
patent: 2-72592 (1990-03-01), None
patent: 01/95400 (2001-12-01), None
K. T. Le Thi et al., “Investigation of the MS-Al2S3systems (M= Ca, Sr, BA) and luminescence properties of europium-doped thioaluminates”,Materials Science&Engineering B14(1992), pp. 393-397.
M. R. Davolos et al., “Luminescence of Eu2+in Strontium and Barium Thiogallates”,Journal of Solid State Chemistry, 83, (1989), pp. 316-323.
Le Mercier Thierry
Le Roux Olivier
Burns Doane Swecker & Mathis L.L.P.
Koslow C. Melissa
Rhodia Electronics and Catalysis
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