Abstract Exploring and designing new luminescent host with rich resource is beneficial to reduce the cost and the large-scale application of luminescent materials. Herein, a series of novel Eu3+-activated KNa5Ca5(CO3)8 red-emitting phosphors with different Eu3+ concentrations were successfully synthesized under mild hydrothermal condition. XRD and SEM characterizations showed that all as-prepared KNa5Ca5(CO3)8:Eu3+ samples crystallized in a hexagonal structure, P63mc (No.186) space-group, and showed monodispersed hexagonal sheet morphologies, within a side length interval about 2–3 μm and a thickness of about 0.6 μm. Eu3+ doping within 6 mol% concentration has little influences on the crystal structure of the host, as indicated by XRD, and FT-IR results, but thermal stability changed as the TG-DTA shown. KNa5Ca5(CO3)8 phosphors with different Eu3+ concentration can emit red-light under effectively excitation by near-UV light. CIE chromaticity coordinates of all KNa5Ca5(CO3)8:Eu3+ phosphors were calculated to locate in red region, and CCT of each sample are in the range from 2815 to 3650 K, very close to the tungsten lamp light. Besides, concentration quenching phenomenon appearing at 5 mol% was found to be the result of electric multipolar interaction of Eu3+ activators, and the decay lifetime was about 1.63 ms, which almost unchanged with Eu3+ doping concentration. Importantly, thermal quenching analysis revealed a good thermal stability with thermal activation energy about 0.216 eV. The results reported here demonstrate that KNa5Ca5(CO3)8 is a promising fluorescent host for LEDs applications.

中文翻译：

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一种新的资源丰富的碳酸盐发光宿主 KNa5Ca5(CO3)8：Eu3+ 激活用于红色磷光的案例研究

摘要 探索和设计资源丰富的新型发光主体，有利于降低发光材料的成本和大规模应用。在此，在温和的水热条件下成功合成了一系列具有不同 Eu3+ 浓度的新型 Eu3+ 激活的 KNa5Ca5(CO3)8 红色荧光粉。XRD 和 SEM 表征表明，所有制备的 KNa5Ca5(CO3)8:Eu3+ 样品均以六边形结构、P63mc（No.186）空间群结晶，并显示出单分散的六边形薄片形态，边长间隔约为 2-3 μm 和约 0.6 μm 的厚度。XRD 和 FT-IR 结果表明，6 mol% 浓度内的 Eu3+ 掺杂对主体的晶体结构几乎没有影响，但热稳定性如 TG-DTA 所示。不同Eu3+浓度的KNa5Ca5(CO3)8荧光粉在近紫外光的有效激发下均能发出红光。计算所有KNa5Ca5(CO3)8:Eu3+荧光粉的CIE色度坐标均位于红色区域，每个样品的CCT在2815-3650K范围内，非常接近钨丝灯的光。此外，发现在 5 mol% 时出现的浓度猝灭现象是 Eu3+ 活化剂的电多极相互作用的结果，衰减寿命约为 1.63 ms，几乎与 Eu3+ 掺杂浓度保持不变。重要的是，热淬火分析显示出良好的热稳定性，热活化能约为 0.216 eV。此处报告的结果表明 KNa5Ca5(CO3)8 是一种很有前途的 LED 应用荧光主体。