Direct Preparation of Strontium Aluminate Phosphor Plate by Reactive Infiltration Method

Abstract

Sr-aluminate phosphor plates were prepared by the infiltration-reaction method. The mixture of SrCO3, Eu2O3, Dy2O3 powders were mixed and coated on the porous alumina plate, followed by heating at 1300°C for 4h under 10%H2+90%N2 gas atmosphere. After processing, the surface part of the Al2O3 plate became dense, ∼20μm thickness. SrAl2O4 and Sr3Al2O6 phases were observed as the product. The coated mixture powder changed to a liquid state and infiltrated into the pores of the alumina plate. During processing, the following reactions occurred; SrCO3→SrO+CO2, SrO+Al2O3→SrAl2O4, 3SrO+Al2O3→Sr3Al2O6. According to the Sr distribution analysis at the dense layer, Sr3Al2O6 and SrAl2O4 phases were mainly formed in the surface-side and Al2O3-side layers, respectively. This plate emits green luminescence by the irradiation of the "black-light". The wave length of the emitted light was in the range of 450–650nm, and the maximum intensity appeared at 520nm. Also, this plate showed green afterglow. The best mixing ratio was Sr/Eu/Dy = 5/1/1. This afterglow intensity decreased from 0.14cdm−2 (0sec.) to 0.01cdm−2 (30sec.). We observed the green afterglow for 3 hours in the dark.