Chornii Vitalii, Terebilenko Kateryna, Gural'skiy Il'ya, Slobodyanik Mykola, Zozulia Valeriia, Shova Sergiu, Zhydachevskyy Yaroslav, Nedilko Serhii G
Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska st., Kyiv 01601, Ukraine.
National University of Life and Environmental Sciences of Ukraine, 15 Heroiv Oborony st., Kyiv 03041, Ukraine.
Dalton Trans. 2024 Sep 24;53(37):15583-15594. doi: 10.1039/d4dt01816h.
A narrow-band green emitting KTb(PO) phosphor has been synthesized by a novel single-crystal growth approach involving the application of an inert flux. Its structural and spectroscopic peculiarities have been systematically studied by means of single-crystal X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy analysis, and diffuse reflectance, infrared and photoluminescence spectroscopy. The layered framework of the title compound is organized by linking together slightly distorted phosphate tetrahedra with non-condensed TbO polyhedra into [Tb(PO)] sheets interconnected by potassium cations. KTb(PO) reveals an intense slow green photoluminescence (PL) (decay time constant is near 2.6 ms) under excitation in the range from VUV (100 nm) up to blue light (484 nm). Intensive narrow lines of the D → F (4f → 4f) radiative transitions in Tb ions form the PL spectra. Besides, fast violet PL (time constant < 20 ns) occurs under PL excitations in a narrow range from 250 to 325 nm. Dependencies of the PL quantum yield, and the green and violet PL decays on the excitation wavelength have been analyzed taking into account the multi-phonons, cross-relaxation processes and exciting light absorption by the inherent defects in the KTb(PO) crystal lattice. The dependency of the complex characteristics of PL quantum yield on the excitation wavelength and violet photoluminescence is ascribed to the formation of Tb ions. The color coordinates and color purity of the emission were estimated for the cases of PL excitation in the 160-371 nm spectral range. It has been shown that these characteristics are similar to or even better than those reported for conventional commercial green phosphors. The high values of correlated color temperature ( > 4863 K) of the emission indicates the potential use of KTb(PO) for enhancing cold-light emitting devices.
通过一种涉及使用惰性助熔剂的新型单晶生长方法合成了一种窄带绿色发光的 KTb(PO₄) 荧光粉。通过单晶 X 射线衍射、扫描电子显微镜、能量色散 X 射线光谱分析以及漫反射、红外和光致发光光谱等手段，对其结构和光谱特性进行了系统研究。标题化合物的层状骨架是通过将轻微扭曲的磷酸四面体与非缩合的 TbO 多面体连接在一起，形成由钾阳离子相互连接的 [Tb(PO₄)] 层。在从真空紫外（100 nm）到蓝光（484 nm）的激发下，KTb(PO₄) 呈现出强烈的慢速绿色光致发光（PL）（衰减时间常数接近 2.6 ms）。Tb 离子中 D → F（4f → 4f）辐射跃迁的密集窄线构成了 PL 光谱。此外，在 250 至 325 nm 的窄范围内进行 PL 激发时会出现快速的紫色 PL（时间常数 < 20 ns）。考虑到多声子、交叉弛豫过程以及 KTb(PO₄) 晶格中固有缺陷对激发光的吸收，分析了 PL 量子产率以及绿色和紫色 PL 衰减对激发波长的依赖性。PL 量子产率的复杂特性对激发波长和紫色光致发光的依赖性归因于 Tb 离子的形成。针对 160 - 371 nm 光谱范围内的 PL 激发情况，估计了发射的色坐标和色纯度。结果表明，这些特性与传统商用绿色荧光粉的特性相似甚至更好。发射的相关色温高值（> 4863 K）表明 KTb(PO₄) 在增强冷发光器件方面具有潜在用途。
