High-sensitive nonthermally coupled upconversion for ultralow temperature sensing  

作　　者：Zhiyuan Cai Zhengce An Haozhang Huang Yu Zhao Bo Zhou 

机构地区：[1]State Key Laboratory of Luminescent Materials and Devices,Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques,and Institute of Optical Communication Materials,South China University of Technology,Guangzhou,510641,China

出　　处：《Journal of Rare Earths》2024年第11期2027-2032,I0001,共7页稀土学报（英文版）

基　　金：Project supported by the National Natural Science Foundation of China (Grant Nos.51972119 and 52272151);the Fundamental Research Funds for the Central Universities (2022ZYGXZR015);the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137)。

摘　　要：Upconversion based nanothermometry has received much attention due to its merits of stability,narrow band emission and rich emission peaks.However,the previous works are mainly focused on the emissions from thermally coupled energy levels which is theoretically limited by Boltzmann distribution theory with resultant low temperature sensitivity in particular at ultralow temperatures.Here we report a LiYF_(4):Yb/Ho@LiYF_(4) core-shell nanostructure to improve the sensitivity at low temperatures by taking advantage of non-thermally coupled energy levels of Ho^(3+).In detail,the green upconversion emission of Ho^(3+)shows an increase with reducing temperature while its red upconversion emission presents a decline during the same process.This is primarily due to the suppression of the non-radiative multiphonon relaxation occurred at the green emitting levels(^(5)F_(4),^(5)S_(2)) and the intermediate level(^(5)I_(6)) at low temperatures.Such a feature contributes to a high relative sensitivity of 7.17%/K at 11 K,much higher than reported values.Our results provide a promising candidate for the development of nanothermometer with high-sensitive low-temperature sensing performance.

关 键 词：UPCONVERSION Nanothermometry Ultralow temperature Nonthermally coupled emissions Rare earths 

分 类 号：TB383.1[一般工业技术—材料科学与工程] TP212[自动化与计算机技术—检测技术与自动化装置]