Abstract Up-converting nanothermometer YF3: 20% Yb3+, 0.5% Tm3+ was obtained via hydrothermal synthesis and a subsequent post-synthesis thermal treatment. The nanomaterial formed a stable colloid and showed (under 975 nm excitation) blue upconversion luminescence visible to the naked eye. The emission spectrum consisted of five thulium ion bands (450–870 nm) and one ytterbium ion band (above ~900 nm). The determined band intensity ratios of the non-thermally coupled levels (non-TCLs), i.e. emission bands of Tm3+ and Yb3+ observed in the visible − NIR ranges, monotonously change with temperature. Using linear fits, the determined band intensity ratios were correlated with temperature, and the relative temperature sensitivities and temperature resolutions were calculated for four of them, associated with the non-TCLs of Yb3+ and Tm3+. Utilizing the 2F5/2 → 2F7/2/3H4 → 3H6 band intensity ratio of Yb3+/Tm3+ (940/800 nm), located within the NIR spectral range of the first biological window, and exhibiting very high signal intensity, the developed nanothermometer has a decent relative sensitivity (Sr ≈ 1% K−1) and excellent temperature resolution (δT ≈ 0.2 K) at 313 K. The obtained material can be used to construct new nanothermometers, useful both in biological experiments and in industrial research.

中文翻译：

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使用 Yb3+ 和 Tm3+ 的非热耦合水平提高在近红外范围内工作的发光纳米温度计的温度分辨率

摘要 上转换纳米温度计YF3：通过水热合成和随后的合成后热处理获得20% Yb3+、0.5% Tm3+。纳米材料形成稳定的胶体并显示（在 975 nm 激发下）肉眼可见的蓝色上转换发光。发射光谱由五个铥离子带（450-870 nm）和一个镱离子带（高于~900 nm）组成。确定的非热耦合能级（非 TCL）的带强度比，即在可见光 - NIR 范围内观察到的 Tm3+ 和 Yb3+ 的发射带，随温度单调变化。使用线性拟合，确定的带强度比与温度相关，并且计算其中四个的相对温度敏感性和温度分辨率，与 Yb3+ 和 Tm3+ 的非 TCL 相关。