Papers by Author: Yang Zhou

Abstract: Long afterglow phosphor is a special energy-saving material, which can store the energy of light irradiation and release light slowly. Ultrafine aluminate long afterglow phosphor is commonly prepared by the jet milling method. This method results in weak brightness, which restricts its application in delicate printing or textiles. In this study, fine particle aluminate phosphor (5μm) was coated by alumina, and then re-reduced under a high temperature. The alumina film works as a barrier layer, which protects the particles from sintering. The re-reduced phosphor had double afterglow brightness, and the size of the particle retained original level. The influences of pH value and KOH adding speed were investigated, the optimized parameters are: pH = 5, KOH adding speed = 2 ml/min.

Abstract: Mg doped BaAl₁₂O₁₉:Mn²⁺ phosphor is one of the most efficient green phosphors for PDP. It is difficult to prepare the phosphor both have small particle size (< 3μm) and high luminescence. In the present work, a BaAl₁₂O₁₉:Mn²⁺ phosphor with small particle size was synthesized by the chemical co-precipitation method. Phase transformation and particle growth process during calcining process were investigated. The nucleation process was also discussed. The results show that, the phase transformation is complicated, the transition phases include BaCO₃, γ-Al₂O₃, BaF₂, BaAl₂O₄ and two phases contain Mn; The BaAl₁₂O₁₉ phase is formed from the reaction between BaAl₂O₄ phase and γ-Al₂O₃ phase, no a-Al₂O₃ phase appears during the entire process; The formation temperature of pure BaAl₁₂O₁₉ phase is 1200°C, which is lower than that in the high-temperature solid state reaction method. High efficiency BaAl₁₂O₁₉:Mn²⁺ phosphor with small particle size (< 2μm) and hexagonal flaky shape can be prepared by this method.