Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India.
Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India.
Chemphyschem. 2020 Aug 4;21(15):1731-1736. doi: 10.1002/cphc.202000198. Epub 2020 Jul 10.
Precise assessment of temperature is crucial in many physical, technological, and biological applications where optical thermometry has attracted considerable attention primarily due to fast response, contactless measurement route, and electromagnetic passivity. Rare-earth-doped thermographic phosphors that rely on ratiometric sensing are very efficient near and above room temperature. However, being dependent on the thermally-assisted migration of carriers to higher excited states, they are largely limited by the quenching of the activation mechanism at low temperatures. In this paper, we demonstrate a strategy to pass through this bottleneck by designing a linear colorimetric thermometer by which we could estimate down to 4 K. The change in perceptual color fidelity metric provides an accurate measure for the sensitivity of the thermometer that attains a maximum value of 0.86 K . Thermally coupled states in Er are also used as a ratiometric sensor from room temperature to ∼140 K. The results obtained in this work clearly show that Yb -Er co-doped NaGdF microcrystals are a promising system that enables reliable bimodal thermometry in a very wide temperature range from ultralow (4 K) to ambient (290 K) conditions.
在许多物理、技术和生物应用中，精确的温度评估至关重要，其中光学测温法因响应速度快、非接触式测量路径以及电磁被动性等特点而受到广泛关注。基于比率感应的稀土掺杂荧光粉在接近和高于室温时非常高效。然而，由于依赖于载流子热辅助迁移到更高激发态，它们在低温下受到激活机制猝灭的限制。在本文中，我们通过设计一种线性比色温度计来展示一种克服这一瓶颈的策略，通过这种温度计，我们可以估计低至 4 K 的温度。感知颜色保真度指标的变化为温度计的灵敏度提供了准确的衡量，其灵敏度最大值为 0.86 K。在室温到约 140 K 的范围内，Er 的热耦合态也被用作比率传感器。本工作的结果清楚地表明，Yb-Er 共掺杂 NaGdF 微晶体是一种很有前途的体系，它能够在从超低（4 K）到环境（290 K）温度的非常宽的温度范围内实现可靠的双模测温。
