Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Red phosphor for cathode ray tubes

A new European capability for producing efficient phosphors involves synthesis and characterization of current, advanced and new phosphors, scaling up of the synthesis of current and advanced phosphors, and optimization of the production parameters, fitting of the phosphor efficiency to the new need of contrast and brightness, characterization and quality control of phosphors in a cathode ray tube, replacement of rare earth matrix for the red phosphor by an alkaline earth matrix, decrease of the doping level of the rare earth activator, research of new families of cathodoluminescent materials such as alkaline earth silicon (or yttrium) sulphides or similar compounds associated with a better knowledge of the luminescent mechanisms.
New synthesis of the current red no mill phosphor yttrium oxygen sulphide with europium with appropriate Commission Internationale d'Eclairage (CIE) colour coordinates and visual efficiency has been carried out. Physicochemical and luminescent properties have been studied. New red phosphor calcium sulphide with europium has been prepared with a choice of the synthesis route, doping agents and concentration. Physicochemical and luminescent properties have been studied. A new industrial red phosphor yttrium oxygen sulphide with europium or calcium sulphide with europium has been prepared and on tube measurements have been made.
Process scale up has been studied and the oxysulphides have been tested on real television screens. It has been necessary to change the usual method of application of the phosphors to the tubes.

Calcium sulphide doped with europium has been synthesized by the flux method and by the solid state reaction. By the first method visual efficiencies as high as 86% have been measured, and by the second method an efficiency of 66% has been obtained on solid solutions. Protection of the calcium sulphide grains has been successfully studied. Both organic and inorganic coatings have been deposited on the grains of phosphors.

Reported by

Thomson CSF
Domaine de Corbeville
91404 Orsay
France
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