Upconversion luminescence enhancement and temperature sensing behavior of F⁻ co-doped Ba₃Lu₄O₉:Er³⁺/Yb³⁺ phosphors

Abstract

A series of Ba 3 Lu 4 O 9 :Er 3+ /Yb 3+ (EYBLO) phosphors co-doped with F À ions were synthesized by a simple solid-state reaction method. The results showed that the primary rhombohedral structure was maintained and the crystal lattice began to shrink when F À ions were introduced into the host matrix to occupy the O 2À site. The agglomerations and the impurities (OH À and CO 2 ) with higher phonon energy on the sample surface could be minimized and the sample crystallinity could be improved. Under 980 nm laser diode excitation, the green and red UC emissions of the EYBLO:0.4F À sample show nearly 5-and 7.5-fold enhancements in contrast to F À -free EYBLO. The upconversion luminescence can be finely tuned from yellow to red light to some extent by increasing F À concentration. Based on pumppower dependence and decay lifetime analysis, the energy level diagram was illustrated and the upconversion energy-transfer mechanism was discussed. The green and red emission enhancements are attributed to the modification of the local crystal field of Er 3+ ions and reduction of crystal site symmetry.The cross-relaxation and back-energy-transfer processes play an important role to enhance the red/ green UC emission intensity ratios. The fluorescence intensity ratio technique was employed to investigate the temperature sensing behavior of the synthesized phosphors. The temperature sensing properties can be enhanced by doping of F À ions, and the maximum sensitivity is found to be 44.57 Â 10 À4 K À1 at 523 K. It is promising to provide an alternative approach for enhancing UC luminescence and the temperature sensitivity in oxide matrixes and then obtain high-quality optical temperature-sensing materials by simply co-doping F À ions.

Concentration and pump power-mediated color tunability, optical heating and temperature sensing via TCLs of red emission in an Er3+/Yb3+/Li+ co-doped ZnGa2O4 phosphor

“…They have obtained larger intensity in the presence of F − ion. 71 The enhancement was also observed due to an increase in the crystallinity of the phosphor via F − doping. In our case, the increase in crystallinity and particle size, enhancement in absorption and reduction in optical band gap collectively improve the population of the excited ions in different higher energy levels, which results in an enhancement in the red UC emission intensity of the phosphor more than two times.…”

Dual mode temperature sensing through luminescence lifetimes of F- and O-coordinated Cr3+sites in fluorosilicate glass-ceramics

“…Accordingly, when the temperature increases, the non-radiative decay will become stronger. Through the deformation of the formulae (7) and (8), the total (experimentally measured) lifetime can be written as:…”

“…[1][2][3] In order to further improve the accuracy and extend the operating temperature regions of optical temperature sensors, researchers have attempted to utilize multi-active-center doped material systems or new host materials for doping active-center ions. [4][5][6][7][8] These attempts involve a variety of temperature sensing mechanisms, providing ample valuable inspiration for the design of new types of temperature sensors. Among the various types of optical temperature sensors, luminescence-lifetime-based sensors 4 make up a large proportion due to their intrinsic immunity to the inuence of external conditions such as those of the excitation beams and optical ber transmission efficiencies.…”

Effects of optical-inert ions on upconversion luminescence and temperature sensing properties of ScVO4:10%Yb3+/2%Er3+ nano/micro-particles

“…40 3. [54][55][56][57] According to Boltzmann distribution theory, the emission intensity ratio (R) of the 522 nm and 554 nm transitions can be written as follows: 43 R ¼…”