Near-Infrared Light-Triggered Visible Upconversion Emissions in Er³⁺/Yb³⁺-Codoped Y₂Mo₄O₁₅ Microparticles for Simultaneous Noncontact Optical Thermometry and Solid-State Lighting

Abstract

The Er3+/Yb3+-codoped Y2Mo4O15 microparticles, which possessed admirable optical thermometric and upconversion (UC) emission behaviors, were synthesized through the traditional sintering technology of the sol–gel route. Under near-infrared (NIR) light excitation, the obtained compounds showed the featured green and red UC emissions of Er3+ ions. The most intense luminescent intensity was detected when the Yb3+ ion content was 40 mol %. Through studying the temperature-dependent UC emission intensity ratio of the monitored green emissions, the optical thermometric properties of the resultant microparticles were investigated. The maximum sensor sensitivity of the studied microparticles with optimum doping concentration was approximately 0.00846 K–1. Moreover, the achieved maximum sensor sensitivity was independent of the dopant content that was identical with the theoretical analysis by taking advantage of the Judd–Ofelt theory. Furthermore, a significant increment in the compounds’ temperature was achieved when the excitation pump power was verified in the range of 320–1040 mW. Ultimately, a green-emitting light-emitting diode device was developed with the aid of synthesized microparticles and a 940 nm NIR chip so as to identify their applicability for solid-state lighting. These aforementioned characteristics make the Er3+/Yb3+-codoped Y2Mo4O15 microparticles not only suitable for noncontacting optical thermometry but also for solid-state lighting.

High-Gravity-Assisted Intensified Preparation of Er-Doped and Yb/Er-Codoped CaF2 Upconversion Nanophosphors for Noncontact Temperature Measurement

“…With the pump power tuned from 600 to 1400 mW, the luminescent profiles remained unchanged whereas the intensities of green and red emissions increased continuously. The mathematic relationship between UC emission intensity ( I ) and pump power is as follows: − …”

“…Figure a,b presents the normalized luminescence spectra (normalized at I ( 4 S 3/2 → 4 I 15/2 )) of CaF 2 :Er 3+ (2%) and CaF 2 :Yb 3+ (10%)/Er 3+ (1%) measured in the temperature range 300–400 K. The relative intensity ratio of the 2 H 11/2 → 4 I 15/2 transition versus 4 S 3/2 → 4 I 15/2 kept increasing with the temperature increase owing to the populations of TCLs following the Boltzmann distribution law , and the efficient energy transfer process between Yb 3+ and Er 3+ . The FIR of the TCLs is defined as follows: ,,, …”

Mn4+, Eu3+ Co-doped K0.3La1.233MgWO6: A Potentially Multifunctional Luminescent Material

“…It is clear that Mn 4+ and Eu 3+ have different thermal quenching properties in the K 0.3 La 1.233 MgWO 6 host, and thus, the fluorescence intensity ratio ( I Mn / I Eu ) will vary with the change of temperature. Therefore, the Mn 4+ and Eu 3+ co-doped K 0.3 La 1.233 MgWO 6 might be used as optical thermometric materials based on fluorescence intensity ratio (FIR), − which has high accuracy and high reliability and might be used in harsh environments …”

Composition Regulation Triggered Multicolor Emissions in Eu2+-Activated Li4(Sr1–xCa1+x)(SiO4)2 for a Highly Sensitive Thermometer

“…Temperature is very important to our human daily life, industrial production, medical diagnosis, and scientific experiment. Recently, the noninvasive luminescent thermometers have been widely studied to replace these traditional thermometers (e.g., liquid-in-glass and thermocouple thermometers) considering their exciting advantages of high precision, fast response, real-time monitoring, etc. , The contactless luminescent thermometer mainly utilizes the fluorescence intensity rate (FIR) technique to analyze the different changing tendencies of emission intensities originating from the two thermally coupled levels of rare-earth ions at high temperature. , Some rare-earth ions, such as Nd 3+ , Tm 3+ , Er 3+ , and Pr 3+ , were revealed to exhibit pairs of thermally coupled levels regarding their small energy separations (i.e., 200 ≤ Δ E ≤ 2000 cm –1 ). − Jeong et al stated that the NaLaMgWO 6 :Er 3+ green phosphors presented maximum relative sensitivity (i.e., S r ) of 1.04% K –1 . Fu et al explored the feasibility of the BiPO 4 :Tm 3+ /Yb 3+ compounds for optical thermometry and found its absolute sensitivity to be 0.00083 K –1 .…”