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Tạp chí khoa học ĐHCT
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Bài báo - Tạp chí
(2017) Trang: 62-67
Tạp chí: Hội nghị về Vật liệu và Công nghệ Tiên tiến, Tổ chức tại Trường Đại học Bách Khoa Hà Nội từ 14-15/8/2017
Liên kết:

A phosphor of the Sr8Al12O24S2 doped Eu2+ (SAOS: Eu2+) were prepared by mild hydrothermal method followed by a multi-steps heat treatment process. The as-prepared powders were first annealed at temperature range of 1100 to 13000C in air ambient and then followed by a reducing process in Ar/H2 to archieve Eu2+ - doped phosphors. It has been found that typical phases of SrSO4, SrAl2O4, SrAl12O18 co-exist in the powders annealed below 12000C. The intermediate phases of Sr4Al6O12SO4 is formed at above 12000C, which is subsequently reduced at 9000C in reducing ambient to form final phase of Sr8Al12O24S2 at second stage. The photoluminescence (PL) emission spectrum shows a yellowish-orange band centered at 612nm, which corresponds to the transition from 4f65d1 to 4f7 of Eu2+. No emission peaks of Eu3+ are observed, revels that Eu3+ is totally reduced to Eu2+ in the samples at second stage. The photoluminescence (PL) excitation spectrum show a broad extending band, peaked at 430, 460 and 490nm which matches the emission of blue light-emitting diodes (blue-LEDs). The critical quenching doping concentration of Eu2+ in host material is about 5% mol which related to a dipole-dipole interaction. The optical properties of remote White-LEDs devices using various mixed content of YAG: Ce3+ and SAOS: Eu2+ were measured using integration sphere tester system. The CCT of mixed phosphor plate at the same 25µm phosphor thickness can decrease from cold white light (approximately 6105K, blue-LED+YAG:Ce3+) to warm white light (2500-3500K); the optimum CRI of 78 achieved with the mixing content of 20%wt SAOS: Eu2+ and 80%wt YAG: Ce3+, which is prefer to indoor lighting application.


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