Papers by Keyword: Zinc Silicate

Abstract: Zinc silicate-based (Zn2SiO4:Eu3+) long afterglow phosphors were fabricated by combustion synthesis and annealing method. The effects of different Zn sources, annealing temperature, Eu3+ additive on the properties of the combustion products have been studied. The results show that, the product is white with ZnO as zinc source while that from Zn(NO3)26H2O is slightly yellow. At higher annealing temperature, the sample is purer. Small amount of Eu2O3 additive did not change the phase composition. The fluorescence spectroscopy shows that, the emission peak of the sample with Eu3+ additive located at 620nm.

Abstract: Zinc silicate-based (Zn2SiO4:Eu3+) long afterglow phosphors were produced by solid state reaction method. The effects of borax and Eu2O3 additive on the properties of fabricated products have been studied. The results show that, there is not much difference in phase compositions within the borax additive amount; however, their SEM morphologies are different. Borax additive can increase the grain size of the product. Some sintering phenomena could be observed in the sample with Eu2O3 addition. The fluorescence spectroscopy results indicate that, the emission peak of the sample with Eu3+ additive located at 612nm, which may be a good candidate for red phosphor applications. The luminescent mechanism of Zn2SiO4:Eu3+ is also discussed.

Abstract: Glasses in the composition range in mol% 35-50 ZnO – 10-15 Al2O3 – 40-55 SiO2 were prepared, undoped and doped with 1 x 1019 and 1 x 1020 Sm3+ per cm3 glass as luminescent species for the visible region, especially for blue and red emission. Phase separation occurs in glass samples with high SiO2 content. SiO2-rich droplets in a Zn2+- Al3+- enriched matrix were formed. Sm3+ ions prefer the Zn2+-Al3+-rich glass matrix. By thermal treatment glass samples were transformed into glass ceramics with the main crystal phases: Zn2SiO4 (willemite), ZnAl2O4 (gahnite) and SiO2-mixed crystals. XRD, SEM and TEM measurements were carried out. The luminescent Sm3+ ions are concentrated in the glass matrix. Photoluminescence excitation and emission spectra were recorded in the UV-VIS-region and the time resolved emission behavior was measured by excitation with a N2-laser at 337 nm. The glasses and glass ceramics have interesting chemical and physical properties, high Tg around 700°C, low coefficient of thermal expansion ~ 4 ppm/K, and high chemical stability.