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NEW RED PHOSPHORS FOR CATHODE RAY TUBES

Objective


Calcium sulphide doped with europium (CaS:Eu) ha been synthesized by both flux and solid-state reaction methods. In the first case, very good results have been obtained.

Visual efficiencies as high as 86%, compared to the standard oxysulphide, have been measured on CaS doped with europium and managenese in the flux method. The solid-state reaction came up with an efficiency of 66% and was obtained on solid-solutions (Ca,Mg)S:Eu.

Protection of the CaS grains was successfully studied. Both organic (PMMA) and inorganic (CaCO3) coatings were deposited on the grains of phosphors.

The project also studied new phosphors like thiosulfides. The results obtained until now are poor. More work is necessary to improve the results.
A NEW EUROPEAN CAPABILITY FOR PRODUCING EFFICIENT PHOSPHORS INVOLVES 3 INDUSTRIAL LEVELS:
I) SYNTHESIS AND CHARACTERIZATION OF CURRENT, ADVANCED AND NEW PHOSPHORS;
II) SCALING UP OF THE SYNTHESIS OF CURRENT AND ADVANCED PHOSPHORS, AND OPTIMIZATION OF THE PRODUCTION PARAMETERS;
III) COSTING OF THE PHOSPHOR, CHARACTERIZATION AND QUALITY CONTROL OF PHOSPHORS IN A CATHODE RAY TUBE.

THE MAJOR OBJECTIVE IS TO FIT THE PHOSPHORS EFFICIENCY TO THE NEW NEED OF CONTRAST AND BRIGHTNESS. AN IMPORTANT COST REDUCTION CAN RESULT:

1) OF THE REPLACEMENT OF THE RARE EARTH METRIX FOR THE RED PHOSPHOR BY AN ALKALINE EARTH SULFIDE,
2) OF THE DECREASE OF THE DOPING LEVEL IN RARE EARTH ACTIVATOR. MOREOVER FUNDAMENTAL RESEARCHES ON NEW FAMILIES OF CATHOLUMINESCENT MATERIALS SUCH AS ALKALINE EARTH GALLIUM SULFIDES OR SIMILAR COMPOUNDS ASSOCIATED WITH A BETTER KNOWLEDGE OF THE LUMINESCENT MECHANISMS MAY ALLOW BETTER YIELDS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Thomson-CSF
Address
173,Boulevard Haussmann 173
75415 Paris
France

Participants (3)

Società per lo Sviluppo Tecnologico dei Materiali Avanzati SpA
Italy
Address
Via Delle Industrie 39
30175 Porto Marghera (Venezia)
UNIVERSITE DE BORDEAUX I
France
Address
Cours De La Libération 351
33405 Talence
Videocolor SpA
Italy
Address
Località Frattarotonda
03012 Anagni Frosinone