Alumina, luminophores and mixed compounds, and associated preparation processes

摘要

The present invention relates to the synthesis of luminophores and of reflective alumina for optimizing the emissive properties of a fluorescent layer.

主权项

1. A process for preparing via the alum route an aluminate luminophore comprised of aggregates having a mean size of about 10 μm and comprised of particles having a mean size of between 0.25 μm and 1.5 μm, said process comprising the steps of:
(a) mixing ammonium alum with at least one rare-earth metal based additive to produce a mixture; (b) calcining said mixture at a first temperature of between 1100° C. and 1200° C. for a time of between 1 hour and 2 hours to produce a calcined mixture; (c) passing said calcined mixture through a grill made of non-contaminating material having a mesh size of between 150 μm and 250 μm; (d) grinding said calcined mixture and passing said calcined mixture through a screen to produce a ground mixture; (e) passing said ground mixture through a grill made of non-contaminating material having a mesh size of between 150 μm and 250 μm; (f) calcining said ground mixture resulting from step (e) at a second temperature of between 1300° C. and 1400° C. for a time of between 3 hours and 5 hours; (g) grinding the ground mixture resulting from step (f); and (h) passing the ground mixture resulting from step (g) through a grill made of non-contaminating material having a mesh size of between 150 μm and 250 μm.