title: Sensitivity Modulation of Upconverting Thermometry through Engineering Phonon Energy of a Matrix.
abstract: Investigation of the unclear influential factors to thermal sensing capability is the only way to achieve highly sensitive thermometry, which is greatly needed to meet the growing demand for potential sensing applications. Here, the effect from the phonon energy of a matrix on the sensitivity of upconversion (UC) microthermometers is elaborately discussed using a controllable method. Uniform truncated octahedral YF3:Er3+/Yb3+microcrystals were prepared by a hydrothermal approach, and phase transformation from YF3to YOF and Y2O3with nearly unchanged morphology and size was successfully realized by controlling the annealing temperature. The phonon energies of blank matrixes were determined by FT-IR spectra and Raman scattering. Upon 980 nm excitation, phonon energy-dependent UC emitting color was finely tuned from green to yellow for three samples, and the mechanisms were proposed. Thermal sensing behaviors based on the TCLs (2H11/2/4S3/2) were evaluated, and the sensitivities gradually grew with the increase in the matrix's phonon energy. According to chemical bond theory and first-principle calculations, the most intrinsic factors associated with thermometric ability were qualitatively demonstrated through analyzing the inner relation between the phonon energy and bond covalency. The exciting results provide guiding insights into employing appropriate host materials with desired thermometric ability while offering the possibility of highly accurate measurement of temperature.
authors.affiliation: National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base) in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Suo
authors.affiliation: National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base) in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Chongfeng
authors.initials: C
authors.lastname: Guo
authors.affiliation: National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base) in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Jiming
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Institute of Modern Physics, Northwest University , Xi'an 710069, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.affiliation: School of Sciences, Chongqing University of Posts and Telecommunications , Chongqing 400065, China.
authors.forename: Chonggeng
authors.initials: C
authors.lastname: Ma
authors.affiliation: National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base) in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Zhao
authors.affiliation: National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base) in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Li
authors.affiliation: National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base) in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University , Xi'an 710069, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Guo
authors.affiliation: ARC Centre of Excellence for Nanoscale Biophotonics (CNBP), Macquarie University , North Ryde 2109, Australia.
authors.forename: Ewa M
authors.initials: EM
authors.lastname: Goldys
keywords: bond covalency; phonon energy; sensitivity; thermometer; upconversion