The present study aims to analyze the tunability of photonic emissions as a function of excitation wavelengths in Fe/Sm co-doped ZnO phosphors. We have investigated the up-conversion (UC) and down-conversion (DC) luminescences in detail along with possible channels for energy transfer and their local electronic structures. These phosphors are polycrystalline with a hexagonal wurtzite structure, and the co-doping of Fe/Sm ions leads the 3D-pyramid like morphology of the ZnO to transform in flower-shaped nanorods. Further, from the UV–Vis spectra, it is found that bandgap contracts due to the formation of defects. The DC emission spectra (λex = 325 nm) show an enhancement of polychromatic emission as a function of the Sm concentration and tune from orange to red along with the transition from the warm to cool region in the Commission International de l'Eclairage 1931 XY spectral chromaticity coordinates. X-ray absorption spectra confirm the presence of Fe2+/Fe3+ ions and Sm3+ ions. Using the decay kinetics and transfer efficiencies, the energy transfer between the host defect levels and dopant ions is explained with the help of the energy level diagram. The UC emission spectra (λex = 980 nm) exhibit monochromatic red emission along with a strong near-infrared emission lying in the cool region with 100% color purity. These phosphors are expected to find applications in solid-state lighting applications, optoelectronics, and biomedical engineering, etc.

中文翻译：

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Fe/Sm 改性 ZnO 荧光粉的激发诱导增强光谱响应和能量转移机制

本研究旨在分析作为 Fe/Sm 共掺杂 ZnO 磷光体中激发波长的函数的光子发射的可调性。我们详细研究了上转换 (UC) 和下转换 (DC) 发光以及能量转移的可能通道及其局部电子结构。这些磷光体是具有六方纤锌矿结构的多晶，Fe/Sm 离子的共掺杂导致 ZnO 的 3D 金字塔状形态转变为花形纳米棒。此外，从 UV-Vis 光谱中发现，由于缺陷的形成，带隙收缩。DC 发射光谱 (λex = 325 nm) 显示多色发射的增强作为 Sm 浓度的函数，并随着从温暖到凉爽区域的过渡从橙色调到红色，在国际委员会 1931 年 XY 光谱中色度坐标。X 射线吸收光谱证实了 Fe2+/Fe3+ 离子和 Sm3+ 离子的存在。使用衰减动力学和转移效率，在能级图的帮助下解释了主体缺陷能级和掺杂离子之间的能量转移。UC 发射光谱 (λex = 980 nm) 表现出单色红色发射以及位于冷区的强近红外发射，色纯度为 100%。这些荧光粉有望在固态照明应用、光电子学和生物医学工程等方面得到应用。