Stabilization of Fluorescent [Ag-m](n+) Quantum Clusters in Multiphase Inorganic Glass-Ceramics for White LEDs

Abstract : Silver quantum clusters ([Ag-m](n+) QCs) are a type of efficient broadband fluorescence centers with m and n related quantum size effects but usually lack chemical and thermal stability. To solve such a problem and exploit [Ag-m](n+) QCs potential applications in white LED lighting, [Ag-m](n+) QCs and rare earth ions (RE3+) were designed to be selectively enriched into B2O3-rich spinodal nanophase separation and SrF2 nanocrystals in fluoroborosilicate multiphase glass-ceramics. In this work, Ag/RE3+-codoped glasses and glass-ceramics with a designed composition were prepared through a melt-quenching method and subsequent heat treatment. The B2O3-rich spinodal nanophase separation and SrF2 nanocrystals were stepwise formed in these glass-ceramics. Taking Ag/E-r3+-codoped glass-ceramics for an example, the special microstructures were clearly revealed by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), and energy-dispersive X-ray spectroscopy (EDX) mappings. By the strategies of controlling [Agl solubility and charge compensating to [AlO4](-), [BO4](-), and [ZnO4](2-) tetrahedra, a large quantity of [Ag-m](n+) QCs were stabilized in the glass networks with regulated m and n. By the strategies of RE3+/Al-3 and Ag+/Na- competitive distribution, the solubility of Ag+ in B2O3-rich glassy phases was effectively increased, and [Ag-m](n+) QCs were eventually stabilized to withstand the postcrystallization procedures at high temperatures up to 650 degrees C. By the multiphase strategy, Ag and RE3+ were selectively partitioned into the B2O3-rich nanosize glassy phases and SrF2 nanocrystals, respectively. Thus, energy transfers (ETs) between [Ag-m](n+) and RE3+ can be well-suppressed to enhance the photoluminescence quantum yields (PL QYs) of the multiphase glass-ceramics. Those engaged [Ag-m](n+) with largely improved white light-emitting diode (WLED) performances, e.g., QY and color rendering index (CRI), in the glass-ceramics. This suggests that Ag/RE3+-codoped glass-ceramics can be ideal candidate phosphors for high-power WLED lighting devices.
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Submitted on : Tuesday, July 9, 2019 - 1:30:43 PM
Last modification on : Tuesday, September 17, 2019 - 3:04:10 PM

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Xiuxia Xu, Junjie Zhao, Xue Luo, Ronghua Ma, Jiangyun Qian, et al.. Stabilization of Fluorescent [Ag-m](n+) Quantum Clusters in Multiphase Inorganic Glass-Ceramics for White LEDs. ACS Applied Nano Materials, American Chemical Society, 2019, 2 (5), pp.2854-2863. ⟨10.1021/acsanm.9b00312⟩. ⟨hal-02177796⟩

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