Objectif The first objective of this project is to develop more reactive rare earth oxide powders with improved morphology and a reduced level of those impurities that have a detrimental effect on the luminescent performance. The second objective is to use these improved rare earth oxide powders to develop a process for the preparation of more efficient luminescent powders with narrower particle size distribution. 1. By improving the quantum yield of the red phosphor YOX and the green phosphor CBT, an increase of 2.5% in luminous efficacy of /80 lamps was reached. 2. The luminous efficacy of YOX, for 254 nm excitation, is decreased, due to competitive absorption by impurities, c.q. transition metal ions and defects, like interstitial oxygen. 3. The green phosphors LAP and CBT are efficiently quenched by Eu3+, due to an electron transfer process. 4. In CBT transition metal ions decrease the luminous efficiency of Ce3+, Gd3+ and Tb3+, since they are incorporated in the lattice, energy transfer to these impurity ions is possible. 5. An amorphous surface layer on a phosphor particle is observed with HR TEM. It is concluded that Cr3+ is not incorporated into either LAP or CBT, but is present in an amorphous second layer. 6. By changing process conditions during the production of the rare earth oxides it is possible to produce these starting materials with improved specifications. 7. Using mixed oxides instead of separate oxides as starting materials the highest quantum yield was found. Mixed oxides have an optimal distribution of the activator, so no concentration quenching will occur on a micro scale. 8. By using mixed oxides in the production of phosphors the grainsize distribution has become narrower and better controlled and so the coating weight was lowered in fluorescent lamps resulting in costprice reduction. 9. Both higher efficacy (lm/W) and costprice reduction will lead to an acceleration of the replacement of incandescent lamps by (compact) fluorescent lamps and thus a considerable energy saving. Champ scientifique engineering and technologymaterials engineeringcoating and films Programme(s) FP2-BRITE/EURAM 1 - Specific research and technological development programme (EEC) in the fields of industrial manufacturing technologies and advanced materials applications (BRITE/EURAM), 1989-1992 Thème(s) Data not available Appel à propositions Data not available Régime de financement Data not available Coordinateur Philips Gloeilampen Fabrieken NV Contribution de l’UE Aucune donnée Adresse 80020 5600 JM EINDHOVEN Pays-Bas Voir sur la carte Coût total Aucune donnée Participants (3) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire RHODIA Chimie SA France Contribution de l’UE Aucune donnée Adresse 18 avenue d'Alsace 92097 Paris la Défense Voir sur la carte Coût total Aucune donnée Rijksuniversiteit Utrecht Pays-Bas Contribution de l’UE Aucune donnée Adresse 3500 UTRECHT Voir sur la carte Coût total Aucune donnée Universidad de Cadiz Espagne Contribution de l’UE Aucune donnée Adresse 40 11150 PUERTO REAL Voir sur la carte Coût total Aucune donnée
