Rare earth activated phosphors coating for photoluminescent textile

PolyU Library Call No.: [THS] LG51 .H577P ITC 2016 Chenxxv, 194 pages :color illustrationsPhotoluminescent textile has attracted increasing interest in recent years as an innovative functional material for anti-counterfeiting, security warning, security lighting and decoration applications. However, there are few scientific studies on the fabrication of photoluminescent textile deposited with photoluminescent thin films by using electron beam evaporation (EBE) technology. Therefore, the purposes of this study are to develop photoluminescent textile by depositing trivalent europium ion doped yttrium oxide (Y₂O₃:Eu³⁺) phosphor thin films onto a quartz fabric substrate with EBE and investigate the microstructure and photoluminescent properties of Y₂O₃:Eu³⁺ films deposited onto quartz fabric. Annealing treatment with muffle furnace and CO₂ laser are carried out on Y₂O₃:Eu³⁺ films deposited onto quartz fabric. A systematic investigation is presented in this research and consists of four parts: (1) the synthesis of Y₂O₃:Eu³⁺ phosphor by NH₄HCO₃-based precipitation method for the evaporated target used in the deposition process; (2) preparation of photoluminescent textile deposited with Y₂O₃:Eu³⁺ films by using EBE; (3) examination of the microstructure and photoluminescent properties of the Y₂O₃:Eu³⁺ films deposited onto quartz fabric and prepared with different deposition parameters and under different annealing conditions; and (4) exploration of a novel photoluminescent textile with effective photoluminescent properties in terms of its functional and aesthetic effects.The results reveal that the synthesized Y₂O₃:Eu³⁺ phosphor with favorable photoluminescent properties is a desirable candidate as the evaporated target in the deposition process. The results also indicate that the Y₂O₃:Eu³⁺ films deposited onto quartz fabric with a substrate temperature of 250℃ exhibit optimal photoluminescent intensity after annealing treatment which is improved by 32.67% as opposed to annealed films grown at room temperature. The maximum photoluminescent intensity of the annealed Y₂O₃:Eu³⁺ films deposited onto quartz fabric is observed with a deposition time of 15 min, which is improved by 124.73% in comparison to a deposition time of 5 min. The emission brightness is optimal when the annealed films are prepared with a deposition current of 140 mA, and the photoluminescent intensity is increased by 6317% when the deposition current is increased from 80 to 140 mA. Both annealing methods can effectively improve the photoluminescent properties of the Y₂O₃:Eu³⁺ films deposited onto quartz fabric. The highest emission brightness of the Y₂O₃:Eu³⁺ films deposited onto quartz fabric is obtained after furnace annealing at 1000℃ for 3 h and CO₂ laser heating with a resolution of 35 dpi for 120 μs, and the photoluminescent intensity is improved by 1234.41% and 366.73%, respectively compared to that of the as-deposited films. This study indicates that EBE is a promising technology for the development of photoluminescent textiles. The experimental results suggest that the improved morphology and crystal properties of the Y₂O₃:Eu³⁺ films are the major reasons for the increased photoluminescent properties of the deposited quartz fabric. The prepared photoluminescent textile that emits a red light has potential applications for anti-counterfeiting, security warning and decoration purposes.Institute of Textiles and ClothingPh.D., Institute of Textiles and Clothing, The Hong Kong Polytechnic University, 2016.Doctorat