Multi‐phase glass‐ceramics containing CaF₂: Er³⁺ and ZnAl₂O₄:Cr³⁺ nanocrystals for optical temperature sensing

Abstract

Oxyfluoride transparent glass-ceramics (GC) containing CaF 2 and ZnAl 2 O 4 nanocrystals have been fabricated with melt-quenching method. By carrying out the heat treatment of the precursor glass (PG), Er 3+ and Cr 3+ were selectively partitioned into CaF 2 and ZnAl 2 O 4 nanocrystals, respectively. The obtained multiphase GC exhibited strong upconversion (UC) fluorescence of Er 3+ as well as intense down-conversion (DC) fluorescence of Cr 3+ . Under 980 nm excitation, the green UC fluorescence of Er 3+ due to 2 H 11/2 , 4 S 3/2 → 4 I 15/2 transition and the red DC fluorescence lifetime of Cr 3+ due to 2 E, 4 T 2 → 4 A 2 transition were found to be highly dependent on the temperature and makes them possibly suitable for Optical Thermometry. With least-square fitting methods, the FIR of Er 3+ from thermally coupled energy states ( 2 H 11/2 and 4 S 3/2 ) produced maximum temperature sensing sensitivity values of 0.33% K −1 at 437 K and 0.36% K −1 at 267 K, respectively. Similarly, fluorescence lifetime of Cr 3+ attributed to the parity forbidden ( 2 E → 4 A 2 ) and spin allowed ( 4 T 2 → 4 A 2 ) produced the maximum temperature sensor sensitivity value equal to 0.67% K −1 at 535 K. K E Y W O R D Sfluorescence, multi-phase glass-ceramics, optical temperature sensing, rare earths, transition metals, upconversion

Surface-enhanced luminescence of Cr3+-doped ZnAl2O4 and MgAl2O4 using Ag@SiO2 and Au@SiO2 core–shell nanoparticles

“…26 For instance, the excited-state lifetimes in some Cr 3+ -doped inorganic phosphors have been reported to be in the millisecond time range. [27][28][29] To the best of our knowledge, surface-enhanced luminescence (SEL) of inorganic phosphors has not been studied. In this work, we report on the SEL of two chromium-doped spinels (CDSs) with lifetimes in the millisecond range at room temperature.…”

Mechanistic insights into defect generation and tuning of optical properties in Zn1−xFexAl2O4(0.01 ≤x≤ 0.40) nanocrystals

“…Matsui et al (2001) observed mechanooptical stress sensing in ZnAl 2 O 4 doped with Mn 2+ . Optical temperature sensing through temperature-dependent fluorescence up-and down-conversion in ZnAl 2 O 4 :Cr 3+ ,Er 3+ , attributed to the selective partitioning of optical centres, was explored by Wadhwa et al (2019). Most recently, saturation absorption of Fe 2+ ions in Fe:ZnAl 2 O 4 was studied using Ho:YAG and Er:YAG lasers by Fedorov et al (2020) for mid-IR laser applications.…”

Structural Origins of BaF2/Ba1 −xRxF2 +x/RF3 Nanocrystals Formation from Phase Separated Fluoroaluminosilicate Glass: A Molecular Dynamic Simulation Study

“…For example, the Ba 2 LaF 7 :Ln 3+ containing glass-ceramics have extraordinary UC luminescence property, being a potentially candidate for random lasing action, [4,5] optical thermometry, [6] and green phosphors in white light-emitting diodes. [9][10][11][12] Previous researches revealed that the unique connection between the chemical state of dopants and topology of the disordered glass structure in oxide glass system. [8] Different luminescent centers have coordination preferences in oxide or fluoride environment.…”

“…Different luminescent centers have coordination preferences in oxide or fluoride environment. Normally, most of the Ln 3+ is found to enrich in the fluoride phase, while the transition metal ions can enrich in the oxide or fluoride phase depending on other glass modifier cations in the composition . Previous researches revealed that the unique connection between the chemical state of dopants and topology of the disordered glass structure in oxide glass system .…”