Abstract

It has great significance to find a path on generating multicolor with one n-UV chip coated with single phosphor. Herein, Eu doped Na₂Al₂B₂O₇ (NAB) phosphor is synthesized by solid state reaction in air atmosphere. Both 4f⁶5d¹ → 4f⁷ transitions of Eu²⁺ (445 nm) and f–f transitions as ⁵D₀ → ⁷F_J (J = 0, 1, and 2) of Eu³⁺ (570–650 nm) have been observed. When increasing Eu doping concentration, both the luminescence intensity and lifetime of Eu³⁺ are increased and no obvious concentration quenching is observed, while the emission strength of Eu²⁺ does not change monotonically but with two remarkable peak values. The optimum doping concentration of Eu is 16%. Furthermore, Eu³⁺ is determined to be from Eu(BO₃) matrix itself, and Eu²⁺ testified by ESR and XPS is created by self-reduction of Eu³⁺ to Eu²⁺ in NAB due to charge compensation. When x ≥ 0.16, the Eu³⁺ ion would rather bond with BO₃ triangles in Eu(BO₃) than stay as Eu²⁺ in AlO₄ tetrahedral in NAB. Furthermore, the as prepared sample shows an excellent thermal stability and the PL quantum efficiencies of NAB: 0.16Eu sample excited by 341 nm and 393 nm are 11.99% and 9.39%, respectively. Additionally, the calculated CIE chromaticity coordinates signify that a couple of colors can be generated by adjusting the excitation wavelength owing to the strength changes between blue and red emissions. Therefore, this novel bicolor phosphor can serve as a potential candidate for w-LEDs applications.

Graphic Abstract

中文翻译：

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单个n-UV激发的蓝色和红色双色发射荧光粉及其在Na 2 Al 2 B 2 O 7中的Eu 3+→Eu 2+的自还原

摘要

找到一条涂有单个荧光粉的n-UV芯片产生多色的途径具有重要意义。在此，通过在空气气氛中的固相反应来合成Eu掺杂的Na ₂ Al ₂ B ₂ O ₇（NAB）荧光体。两个4 ˚F ⁶ 5 d ^1个 →4F ^7个的Eu的跃迁²⁺（445纳米）和˚F - ˚F转变为⁵ d ₀  →  ⁷ ˚F _Ĵ铕（J = 0,1，和2）³⁺（570–650 nm）已观察到。当增加Eu掺杂浓度时，Eu ³⁺的发光强度和寿命都增加，并且没有观察到明显的浓度猝灭，而Eu ²⁺的发射强度不是单调变化，而是具有两个明显的峰值。Eu的最佳掺杂浓度为16％。此外，Eu的³⁺被确定为选自Eu（BO ₃）基质本身和Eu ²⁺作证通过ESR和XPS由自还原的Eu创建³⁺与Eu ²⁺由于电荷补偿在NAB。当x≥0.16，Eu的³⁺离子宁愿键与BO _3个中的Eu三角形（BO ₃）比在NAB中的AlO ₄四面体中以Eu ^2+形式保留。此外，所制备的样品显示出优异的热稳定性，并且NAB的PL量子效率：由341nm和393nm激发的0.16Eu样品分别为11.99％和9.39％。另外，由于蓝色和红色发射之间的强度变化，计算出的CIE色度坐标表示可以通过调整激发波长来生成几种颜色。因此，这种新颖的双色磷光体可用作w-LED应用的潜在候选者。

图形摘要