Sensitization of lanthanide-based phosphors by transition metals for high-brightness tunable thermometers (SensiTherm)

本项目的主要目标是通过过渡金属离子的敏化来提高镧系光学温度计的光致发光性能。利用过渡金属离子明显较高的吸收截面，可以显著增强稀土离子的发射强度，这将增加温度计提供的信号电平。此外，由于敏化剂到激活剂的能量传递强烈依赖于温度，过渡金属离子对稀土发光的敏化将为提高共掺发光温度计的温度灵敏度开辟一条新的途径。为了实现这一目标，将详细了解微晶颗粒中过渡金属离子对稀土元素的敏化过程。材料参数如局域晶场、声子能量、掺杂浓度、激活剂和敏化剂激发态之间的能级差等对温度敏化过程的影响使得控制和有意设计具有高发射强度和对温度变化高度敏感的发光温度计成为可能。为了研究能量转移，将在弗罗茨瓦夫合成微晶样品，并将在马格德堡使用分散粒子方法和量子产额测量来研究微晶样品的光谱性质，以明确量化吸收、能量转移和发射过程。将通过系统地探测一系列组合来研究宿主、敏化剂和激活剂相关的参数。将测量吸收截面、能量转移率以及辐射和非辐射去激发率，这也将作为在弗罗茨瓦夫发展的理论模型的比较。这些速率还将在一定范围的掺杂剂浓度(敏化剂和激活剂)、激发功率密度和温度下进行测量，以调查每个参数对敏化过程的影响。拟议的项目将弗罗茨瓦夫在过渡金属和稀土掺杂化合物的合成、结构表征和理论方面的专业知识与Magdeburg在基于探测温度控制流体流动系统中分散颗粒发光的先进光谱技术方面的专业知识结合在一起。该项目的实施将对过渡金属和稀土元素之间的能量转移过程进行广泛的表征，以便从根本上理解并提供具有增强特性(更合适的激发窗口、更高的发射强度、更高的温度灵敏度)的发光温度计，这将极大地促进许多科学领域的进步，其中温度是最重要的特性。

The main objective of this project is to enhance the photoluminescence properties of lanthanide-based optical thermometers via sensitization by transition metal ions. Taking advantage of the significantly higher absorption cross section of transition metal ions, the emission intensity of the lanthanide ions can be significantly enhanced, which will increase the signal levels offered by the thermometers. In addition, because the energy transfer from sensitizer to activator is strongly temperature-dependent, the sensitization of lanthanide emissions through transition metal ions will open a new path to enhance the temperature sensitivity of co-doped luminescent thermometers. To achieve this goal a detailed understanding of the sensitization process of lanthanides by transition metal ions in microcrystalline particles will be developed. The influence of material parameters such as local crystal field, phonon energy, dopant concentration, and energy level difference between excited states of activator and sensitizer on the temperature-dependent sensitization process enables the control and intentional design of luminescent thermometers with high emission intensity and high sensitivity to temperature changes. To investigate the energy transfer, microcrystalline samples will be synthesized in Wroclaw, and the spectroscopic properties will be investigated in Magdeburg using dispersed particle methods and quantum yield measurements to unambiguously quantify the absorption, energy transfer and emission processes. Host, sensitizer and activator dependent parameters will be investigated by systematically probing a range of combinations. The absorption cross section, the energy transfer rate, as well as radiative and non-radiative de-excitation rates will be measured, which will also serve as a comparison for theoretical models developed in Wroclaw. Those rates will also be measured over a range of dopant concentrations (sensitizer and activator), excitation power densities and temperatures to investigate the effect of each parameter on the sensitization process. The proposed project brings together the expertise of Wroclaw in the synthesis, structural characterisation and theory of transition metal and lanthanide doped compounds, with that of Magdeburg in advanced spectroscopic techniques based on probing the luminescence of dispersed particles in temperature-controlled fluid flow systems. Implementation of this project will provide an extensive characterization of energy transfer processes between transition metals and lanthanides, for both fundamental understanding as well as to provide luminescence thermometers with enhanced characteristics (more suitable excitation window, higher emission intensity, higher temperature sensitivity) which will greatly contribute to the progress of many fields of science for which temperature is a property of foremost importance.