Preparation Of Spherical Bamgal₁₀o₁₇: Eu～(2+) Blue Phosphor For Pdp Application By The Controlled Reaction-precipitation Process

Plasma Display Panels (Plasma Display Panel, PDP) are characterized with large screen, wide visual angle, high resolution, light and quick response and have become one of hotspots in the big screen technological field. BaMgAl₁₀O₁₇:Eu²⁺ (BAM) has been widely used as a bule-emitting phosphor in plasma display panel (PDP) because of its high quanta efficency, chromaticity and high luminescence efficency under vacuum ultraviolet (VUV). BAM is currently prepared by high temperature solid reactions in industry for many years.Although this technical process is simple and easy for scaling-up; it needs holding a long time at 1600℃.During the process, some raw materials can't react adequately which results in many impure phases such asα-Al₂O₃, BaAl₂O₄ and MgAl₂O₄, these impure phases are proved to absorb ultraviolet radiation and visible light which leads to degradations of phosphor's luminescence performances.And what's more, the BAM powders gain a hexagon sheet structure and wide size distribution of the particle diameters.The operational performance of this kind of powders is poor and at the same time, the powders need further ball-milling to reduce the particle diameter. But the ball-milling will destruct the powder's crystal structure and result in rapid degradation of its fluorescence performances. Therefore, it is meaningful in reality and theory to develop a novel process for "non-ball-milling" and high performance phosphors.The present paper studied the preparation of spherical BAM powders by the controlled reaction-precipitation process with raw materials of aluminum ammonium sulfate, magnesium nitrate, barium nitrate, sodium carbonate aqueous solutions.The morphologies, composition and structure of the precursors and the resultant products derived from thermal decomposition of the precursors have been characterized by scanning electron microscopy (SEM) , X-ray diffraction (XRD).The thermal decomposition process of the precursor was studied by thermogravimetry-differential scanning calorimetry (TG-DSC). And the size distribution of the precursor particle was measured by particle size analyzer.And the BAM powders' fluorescence performance was measured by fluorescence Spectrophotometer and PMS-3 system. The research results show that pH value, time of the grains in the reactor , molar ratios of metal ions in aqueous solution, the dopping quantity of rare earth Eu ions and the heat treatment temperature and time were the main factors for the precise control of composition and structure of the precursor and fluorescence performance of the final products. The experimental results show that blue-emitting phosphor BaMgAl₁₀O₁₇:Eu²⁺ is characterized with relative luminescence lighteness 104%, color coordinate value x=0.1446, y=0.0620, correlated color temperature 25000K, D50=7.20μm, the mean size 7.50μm, particle size distrubtion 5～8μm, emission spectrum wavelength 449nm, and thermal degradation is better than the BAM blue phosphor synthesized by solid reaction.