Abstract Inorganic upconverting nanoparticles that can be excited with 808 nm laser radiation are gaining much attention recently. Living tissues, as well as water do not heat up as intensively when embedded upconverting nanoparticles are excited under such wavelength if compared to commonly used 980 nm laser radiation for excitation. To this end, a series of NaGd0.995-xYbxNd0.005F4 nanoparticles were synthesized in order to investigate energy transfer efficiency between Nd3+ and Yb3+ dopants under 808 nm laser excitation to better suit biological applications. The impact of Yb3+ concentration increase on crystal phase formation as well as downconversion (DC) properties was investigated. Temperature dependent luminescence measurements in NIR region revealed that no thermal quenching of Nd3+−Yb3+ pair in NaGdF4 system was observed in the entire 77–500 K temperature range. Finally, Er3+ ions were introduced in the investigated system in order to obtain multiple excitation and visualisation tool with performance in both VIS and NIR regions. The effective energy difference (ΔE) was also calculated from the thermally coupled levels (TCLs) of Er3+. The promising results and observations of synthesized compounds will be discussed, as NaGd0.475Yb0.5Er0.02Nd0.005F4 has a potential to be used as a luminescent temperature sensor.

中文翻译：

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NaGdF4:Nd3+, Yb3+, Er3+ 上转换纳米粒子中 Nd3+→Yb3+ 能量转移效率的温度诱导发射增强和研究

摘要 可被 808 nm 激光辐射激发的无机上转换纳米粒子最近备受关注。与常用的用于激发的 980 nm 激光辐射相比，当嵌入的上转换纳米粒子在这种波长下激发时，活组织和水不会被强烈加热。为此，合成了一系列 NaGd0.995-xYbxNd0.005F4 纳米颗粒，以研究在 808 nm 激光激发下 Nd3+ 和 Yb3+ 掺杂剂之间的能量转移效率，以更好地适应生物应用。研究了 Yb3+ 浓度增加对晶相形成以及下转换 (DC) 特性的影响。NIR 区域的温度相关发光测量表明，在整个 77-500 K 温度范围内未观察到 NaGdF4 系统中 Nd3+-Yb3+ 对的热猝灭。最后，在所研究的系统中引入 Er3+ 离子以获得在 VIS 和 NIR 区域均具有性能的多重激发和可视化工具。有效能量差 (ΔE) 也由 Er3+ 的热耦合能级 (TCL) 计算得出。将讨论合成化合物的有希望的结果和观察结果，因为 NaGd0.475Yb0.5Er0.02Nd0.005F4 具有用作发光温度传感器的潜力。有效能量差 (ΔE) 也由 Er3+ 的热耦合能级 (TCL) 计算得出。将讨论合成化合物的有希望的结果和观察结果，因为 NaGd0.475Yb0.5Er0.02Nd0.005F4 具有用作发光温度传感器的潜力。有效能量差 (ΔE) 也由 Er3+ 的热耦合能级 (TCL) 计算得出。将讨论合成化合物的有希望的结果和观察结果，因为 NaGd0.475Yb0.5Er0.02Nd0.005F4 具有用作发光温度传感器的潜力。