Zaldo Carlos, Cascales Concepción
Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, c/ Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain.
Phys Chem Chem Phys. 2014 Nov 14;16(42):23274-85. doi: 10.1039/c4cp03616f.
Yb(3+)-sensitized, Ln(3+)(Er(3+), Pr(3+))-doped Y6O5F8 micron-sized bundles of highly crystalline individual nanotubes have been prepared through hydrothermal syntheses at 185 °C. The inhomogeneous broadening observed in their optical spectra is associated with the large distribution of crystal fields around Y(3+)(Ln(3+)) sites in the orthorhombic Pbcm Vernier-type Y6O5F8 host. Based on ratiometric analyses of the thermal evolution of intensities of near-infrared NIR (∼978 nm)-excited green upconversion emissions corresponding to (2)H11/2, (4)S3/2 → (4)I15/2 Er(3+) transitions, the temperature sensing behaviour of Er, Yb:Y6O5F8 was studied. This thermal sensor exhibits a very high sensitivity S = 0.0060 K(-1) at physiological temperatures (22-50 °C), which surpasses the S value found for Er, Yb:β-NaYF4 at these temperatures, and a maximum S = 0.0082 K(-1) at ∼225 °C. Also under NIR diode laser excitation, the color of the upconverted light from codoped Pr, Er, Yb:Y6O5F8 nanotubes can be selected by the control of the Pr(3+) concentration and by the excitation regime and power density. Samples with low Pr(3+) concentration emit green light, and the selection between bluish-green light and white light has been demonstrated with high Pr(3+) concentration (2 mol%), under pulsed or continuous wave excitation, respectively.
通过在185℃下进行水热合成，制备出了Yb(3+)敏化、Ln(3+)(Er(3+), Pr(3+))掺杂的Y6O5F8微米级高度结晶的单根纳米管束。在其光谱中观察到的非均匀展宽与正交晶系Pbcm游标型Y6O5F8基质中Y(3+)(Ln(3+))位点周围晶体场的大分布有关。基于对近红外NIR（978nm）激发的对应于(2)H11/2、(4)S3/2→(4)I15/2 Er(3+)跃迁的绿色上转换发射强度热演化的比率分析，研究了Er, Yb:Y6O5F8的温度传感行为。这种热传感器在生理温度（22 - 50℃）下表现出非常高的灵敏度S = 0.0060 K(-1)，超过了在这些温度下Er, Yb:β-NaYF4的S值，并且在225℃时最大S = 0.0082 K(-1)。同样在近红外二极管激光激发下，通过控制Pr(3+)浓度、激发方式和功率密度，可以选择共掺杂Pr, Er, Yb:Y6O5F8纳米管上转换光的颜色。低Pr(3+)浓度的样品发射绿色光，在高Pr(3+)浓度（2 mol%）下，分别在脉冲或连续波激发下，已证明可以在蓝绿色光和白色光之间进行选择。
