Enhancing thermal sensitivity in α-NaLuF4:Yb3+, Er3+ upconversion nanocrystals

• Published in: Journal of fluorine chemistry Vol. 192; pp. 41 - 47
• Main Authors: Lin, Hao, Xu, Dekang, Li, Anming, Yang, Shenghong, Zhang, Yueli
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2016
• Subjects: Fluorescence intensity ratio; Hydrothermal method; Optical temperature sensor; Upconversion; α-NaLuF4; Fluorescence intensity ratio; α-NaLuF4; Upconversion; Hydrothermal method; Optical temperature sensor
• ISSN: 0022-1139; 1873-3328
• DOI: 10.1016/j.jfluchem.2016.10.016

The enhanced sensitivity of α-NaLuF4:Yb3+, Er3+ nanocrystals through the increase of NaF content and annealing process. [Display omitted] •α-NaLuF4:Yb3+, Er3+ nanocrystals were achieved through a hydrothermal method with the assistance of citric acid.•The sensitivity of green-based sensor is enhanced by simply adding different NaF contents in the initial reaction solution, and the obtained maximum sensitivity is 0.0022K−1 at 298K.•For the annealed sample, the maximum sensitivity can reach 0.0030K−1 at 298K.•The mechanism of the increasing sensitivity is mainly attributed to the enhancement of emission cross section ratio (σH/σS). α-NaLuF4:Yb3+, Er3+ nanocrystals were achieved through a hydrothermal method with the assistance of citric acid. Under 980nm excitation, the temperature dependence of 523nm and 543nm upconversion emissions of Er3+ was studied from 150K to 298K. The intensity ratio of 2H11/2→4I15/2 to 4S3/2→4I15/2 increases with elevated temperature for the as-prepared samples. Based on the fluorescence intensity ratio technique, we report the enhanced sensitivity of green-based sensor by simply adding different NaF contents in the initial reaction solution, and the obtained maximum sensitivity is 0.0022K−1 at 298K. Moreover, for the annealed sample, the maximum sensitivity can reach 0.0030K−1 at 298K. The mechanism of the increasing sensitivity is discussed in details, which is mainly attributed to the enhancement of emission cross section ratio (σH/σS). This study not only makes α-NaLuF4:Yb3+, Er3+ nanocrystals a promising candidate for the luminescent nanothermometers, but also provides a general and effective approach for enhancing the sensitivity of optical temperature sensors.