基于荧光温度特性的高灵敏度温度探测新机制和新材料研究

Temperature is a significant parameter for determining the state of matter in physics, chemistry, bioscience, as well as engineering and technical fields. It is of great significance to explore temperature sensing materials with high sensitivity, high spatial and time resolutions, and stable performance. The fluorescence intensity ratio (FIR) technique based on the thermally coupled energy levels is an appreciated way of measuring temperature, due to its advantage of self-calibration. However, the meaningful improvement for temperature sensitivity based on 4f-4f transition in temperature-measurement materials is greatly restricted, which is ascribed to thermal coupling principle, heating effect and weak FIR. .In order to realize a meaningful breakthrough, this research project focuses on the following three aspects: (1) To achieve temperature sensing with high sensitivity and negligible heating effect by utilizing the excitation of temperature dependent population of thermal excited states; (2) To explore the mechanism of non 4f-4f transition so as to increase the energy gap while maintaining the scale of intensity ratio (such as in some Sm2+ and Cr3+ activated materials); (3) To explore other mechanisms based on energy transfer, multiphonon process and ladder-level assisted thermal coupling. It is expected that some stable thermographic materials of high sensitivity, spatial and time resolution will be obtained based on those novel mechanisms. Throughout experimental characterization and verification will be performed on those materials to confirm their advantages.

温度是物理、化学、生命科学和工程技术领域极其重要的参量。抗干扰、高灵敏度、高空间分辨率和快速响应的温度传感具有重要科学意义和应用价值。基于热耦合能级的荧光强度比测温因其自校准优势，成为一种具有重要前景的温度传感手段，但现有机制受热耦合、加热效应和强度比过小等制约，其灵敏度难以进一步提升。拟从如下三方面突破这些局限性：(1) 探索把激发基态变成激发占据数剧烈依赖温度的低激发态的温度探测机制；(2) 探索突破4f(n)能级局限后，使得热耦合能级间隔大大增加同时热耦合上能级的跃速率相对下能级具有量级提升的离子（如Sm2+、Cr3+）和合适基质，大幅提高灵敏度；(3) 研究利用能量传递、多声子弛豫等动力学过程或阶梯能级辅助热耦合等的荧光温度探测机制和材料。预期在三个方面建立提升温度探测灵敏度的具体机制并得到一系列性能优异的测温材料，并通过实验验证其消热效应、抗干扰、高空间分辨和快速响应特性。

在物理学、化学、生物医学及工程技术领域，温度是确定物质状态最重要的参量之一。研制出抗干扰、高灵敏度、高空间分辨率和快速响应的温度传感具有的重要科学价值。目前基于热耦合能级的荧光强度比测温因其自校准优势，成为一种具有重要前景的温度传感手段，但现有机制受热耦合、加热效应和强度比过小等制约，其灵敏度难以进一步提升。为此本项目从固体发光的原理出发，进行根本性的突破设计，建立了2种新的测温机制，并在新机制的指导下，获得一系列满足各种温度范围的高灵敏度、快速响应、高空间分辨率的温度探测材料。.本项目取得的重要结果及科学意义如下：（1）研究激发温度依赖的Sm3+的低激发态能级6H7/2,9/2和Eu3+的低激发态能级7F2，分别实现了高灵敏度低热效应的温度探测工作，建立了把激发基态变成激发占据数剧烈依赖温度的低激发态的温度探测机制，此机制不受热效应干扰，且荧光强度是随温度上升而增强的（通常荧光会随温度而热猝灭），因此获得的温度灵敏度、精度以及空间分辨率更高。（2）研究Tb3+与Eu3+的能量传递机理以及Tb3+和Ho3+的7F6–5D4 (Tb3+) 和5I8–5F4, 5S2 (Ho3+)的激发以及5D4–7F6 (Tb3+) 和 5F5–5I8 (Ho3+)的发光，建立了利用能量传递、多声子弛豫等动力学过程或阶梯能级辅助热耦合等的荧光温度探测新机制。（3）在新机制指导下，对NaBaLa2(PO4)3:Sm3+、 LiLaMgWO6:Eu3+、KLa5O5(VO4)2:Yb3+、Ca8ZnLa1-xEux(PO4)7荧光粉、Ca8Eu2(PO4)6O2 、Ca8Tb2(PO4)6O2系列透明玻璃陶瓷，以及LuVO4:Yb3+/Er3+@SiO2纳米和Ln-BDC-F4配合物等优秀材料的光学和温度荧光特性都进行了研究。获到了多种具有潜在应用价值的高灵敏度的温度探测材料，具有较好的应用前景。