Tunable LLP via Energy Transfer between Na2鈥?i>y(Zn1鈥?i>xGax)GeO4 Sosoloid Host and Emission Centers with the Assistance of Zn Vacancies

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• 作者：Ting Wang ; Wenjuan Bian ; Dacheng Zhou ; Jianbei Qiu ; Xue Yu ; Xuhui Xu
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：June 25, 2015
• 年：2015
• 卷：119
• 期：25
• 页码：14047-14055
• 全文大小：576K
• ISSN：1932-7455

文摘

A series of sodium zinc gallogermanate sosoloid Na_2鈥?i>y(Zn_1鈥?i>xGa_x)GeO₄: yTb³⁺ (x = 0, 0.1, 0.12, 0.15, 0.18, and 0.20; y = 0, 0.01, 0.02, 0.03, and 0.04) samples were successfully synthesized and their luminescence properties were investigated. It was found that Zn vacancies could be the predominant contribution to the enhancement of PL and LLP intensities when Ga³⁺ ions were introduced as solute atoms substituted the crystal sites of Zn²⁺ in Na₂ZnGeO₄ host. Zn vacancies act not only as an exciton energy-level participated in the PL process but also as trapping centers contributed to the LLP process. Furthermore, the energy transfer processes from Na₂(Zn_0.8Ga_0.2)GeO₄ host to Tb³⁺ ions in PL and LLP were identified. Accordingly, the LLP colors changed from blue to green with increasing concentration of Tb³⁺ and the mechanism of which was proposed. Besides, after irradiation with 800 nm femtosecond pulsed laser, a blue upconversion LLP phenomenon was clearly observed in Na₂(Zn_0.8Ga_0.2)GeO₄ for the first time. Analysis suggested that multiphoton absorption process was dominant in this upconversion luminescence, and subsequently the carriers excited into conduction band were captured by the trapping centers. Then the realization of LLP was due to the thermal stimulated recombination of holes and electrons at traps. Our results indicated that the blue-green emitting phosphor of Na₂(Zn_0.8Ga_0.2)GeO₄: Tb³⁺ could be a new member in the family of LLP materials, which could also provide potential applications in the fabrication of optical memory.