Effect of Mn2+ on Upconversion Emission, Thermal Sensing and Optical Heater Behavior of Yb3+ - Er3+ Codoped NaGdF4 Nanophosphors

Abstract

In thiswork, we investigate the influence of Mn 2+ on the emission color, thermal sensing and optical heater behavior of NaGdF 4 : Yb/Er nanophosphors, which the nanoparticles were synthesized by a hydrothermal method using oleic acid as both a stabilizing and a chelating agent. The morphology and crystal size of upconversion nano particles (UCNPs) can be effectively controlled through the addition of Mn 2+ dopant contents in NaGdF 4 : Yb/Er system. Moreover, an enhancement in overall UCL spectra of Mn 2+ doped UCNPs for NaGdF 4 host compared to the UCNPs is observed, which results from a closed back-energy transfer between Er 3+ and Mn 2+ ions ( 4 S 3/2 (Er 3+ ) → 4 T 1 (Mn 2+ ) → 4 F 9/2 (Er 3+ )). The temperature sensitivity of NaGdF 4 :Yb 3+ /Er 3+ doping with Mn 2+ based on thermally coupled levels ( 2 H 11/2 and 4 S 3/2 ) of Er 3+ is similar to that particles without Mn 2+ in the 303–548 K range. And the maximum sensitivity is 0.0043 K −1 at 523 K for NaGdF 4 :Yb 3+ /Er 3+ /Mn 2+ . Interestingly, the NaGdF 4 :Yb 3+ /Er 3+ /Mn 2+ shows preferable optical heating behavior, which is reaching a large value of 50 K. These results indicate that inducing of Mn 2+ ions in NaGdF 4 :Yb 3+ /Er 3+ nanophosphors has potential in colorful display, temperature sensor.

Low-temperature open-air synthesis of PVP-coated NaYF 4 :Yb,Er,Mn upconversion nanoparticles with strong red emission

“…This trend was reflected in a shift towards higher 2θ angles for all samples between 0 and 35 mol% Mn 2+ , with a similar reversal for 40% Mn 2+ (see electronic supplementary material, figure S8c,d,f,g,h). Similar shifts in 2θ angle have been reported for upconversion materials co-doped with Fe 3+ and Mn 2+ [55,[57][58][59][60].…”

Upconversion Thermometry Using Yb3+/Er3+ Co-Doped KY3F10 Nanoparticles

“…In general, information about the thermometric performance (thermal sensitivity, S r ) of the upconverting nanosensors is inferred from the fluorescence intensity ratio (Δ) of thermally coupled energy levels of the Ln 3+ ions. Several studies have reported that the thermometric parameter Δ, appears to be reliant on the type of host, − type of dopant ion and their concentrations, , size of the nanoparticles, , surface functionalization, core–shell structure, , incorporation of transition metals, − laser excitation density, and modification of the energy transfer processes − (Table ). As such, detailed studies involving optimization of the chemical and spectroscopic properties of UCNP-based sensors have been performed to increase the operating temperature sensitivity and temperature resolution to fulfill the specific needs of given applications.…”

NIR-II Upconversion Photoluminescence of Er3+ Doped LiYF4 and NaY(Gd)F4 Core-Shell Nanoparticles

“…Furthermore, the photo-luminescence of rare earth is extremely stable, and it could not be affected by blinking or photobleaching ( Shao et al, 2018 ; Song et al, 2019 ). These advantages make rare earth elements perfect candidates for light-triggered diagnostics and therapy ( Chen et al, 2014 ; Shao et al, 2016 ; Qiang and Wang, 2019 ; Wang et al, 2020 ). As an unusual anti-stokes process, photon upconversion (UC) refers to converting several low-energy photons to one high-energy photon ( Zhou et al, 2015 ; Wei et al, 2016 ).…”