Color-Tunable Upconversion Luminescence and Multiple Temperature Sensing and Optical Heating Properties of Ba₃Y₄O₉:Er³⁺/Yb³⁺ Phosphors

Abstract

Upconversion (UC) luminescence materials doped with rare earth ions are extensively investigated as optical temperature probes by the fluorescence intensity ratio technique. However, most Er 3+ -doped materials are still suffering from low sensing sensitivity. In the present study, we attempt to develop high-sensingsensitivity Er 3+ -doped materials based on the thermally coupled energy levels (TCLs) from Stark sublevels as well as the properties at subzero temperatures, for which there is continuous lack of research. Er 3+ /Yb 3+ codoped Ba 3 Y 4 O 9 (BYO) phosphors were produced via a solid-state reaction. Excited by 980 nm, various output colors, including bright green, yellow, and red, in BYO:Er 3+ /Yb 3+ phosphors as well as the relative emission intensities could be regulated through altering Yb 3+ concentrations. Subsequently, on the basis of all 12 pairs of TCLs especially from Stark sublevels of 2 H 11/2 , 4 S 3/2 , and 4 F 9/2 of Er 3+ ions, multiple temperature-sensing performances are evaluated over a wide range of 73−573 K. The results show that the maximum sensitivity of the 2 H 11/2 and 4 S 3/2(1) levels is approximately 1-fold higher than that of traditional TCLs of 2 H 11/2 / 4 S 3/2 at elevated temperature and the maximum sensitivity based on the 2 H 11/2(1) and 2 H 11/2(2) levels is more than 12 times higher than that of the traditional TCLs of 2 H 11/2 / 4 S 3/2 at subzero temperature. Therefore, it is expected to realize high-sensitivity temperature detection from subzero to elevated temperatures by combining two pairs of different TCLs. In addition, the potential of Er 3+ / Yb 3+ codoped BYO phosphors to be used as an optical heater is studied. The generated temperature can be accurately monitored by BYO:Er 3+ /Yb 3+ phosphors and regulated by adjusting the excitation power, which indicate that BYO:Er 3+ /Yb 3+ phosphors can be used as an optical heating device.

Manipulation of upconversion property and enhancement of sensitivity by tailoring the local structure

“…The results prove that higher S A can be achieved in the two‐phase coexistence system contrasting to the single host due to the different thermal response behaviors of the two hosts. Compared with other Er 3+ ‐based optical thermometers presented in Table 4, the S A is comparable to those in Ba 3 Y 4 O 9 , 15 NaYF 4 , 61 Ba 2 In 2 O 5 , 62 NaGaF 4 , 63 and NaYTiO 4 64 hosts, but lower than those in Gd 2 ZnTiO 6 , 18 Bi 5 IO 7 , 54 and Na 0.5 Gd 0.5 MoO 4 60 hosts. On the other hand, the maximum S A is obtained at lower temperature with the increasing of La 3+ concentration (520 K for x = 0.2 and 0.4, 450 K for x = 0.6, and 420 K for x = 0.8).…”

“…However, the S A value is restricted by the constant energy gap of the TCLs, it means that high S A is unable to be achieved in most Yb 3+ and Er 3+ co‐doped materials. To tackle this problem, many strategies have been proposed, such as choosing a suitable host, 12 forming a core‐shell structure, 13,14 utilizing the sub‐Stokes level, 15,16 adding transition metal ions, 17 and dealing with several sections 18‐20 . In our previous work, we proposed a feasible route based on the different thermal response behaviors of various hosts to improve the S A value in two‐phase coexistence system 21 …”

Exploring the Impact of Structure-Sensitivity Factors on Thermographic Properties of Dy3+-Doped Oxide Crystals

“…When discussing our results, we refer to the luminescence spectra presented in Figures 6-10 and the energy level scheme in Figure 11 that was constructed based on the low temperature absorption spectra shown in References [31][32][33][34][35]. [28] -0.41 GdVO 4 [22] 1.80 -Na 5 La 0.5 Dy 0.5 (WO 4 ) 4 [30] 1.80 0.30 NaDy(MoO 4 ) 2 [30] 0.75 0.38 YNbO 4 [24] 1.40 0.36 Y 3 Al 5 O 12 [28] -0.44 La 3 Ga 5.5 Ta 0.5 O 14 [25] 1.47 0.34 BaYF 5 [26] 1.10 0.25 Gd 2 Ti 2 O 7 [27] 1.20 -K 3 Y(PO 4 ) 2 [45] 1.31 -Ba 3 Y 4 O 9 [46] 1.34 - [30].…”

Controllable crystal form transformation and luminescence properties of up-conversion luminescent material K3Sc0.5Lu0.5F6: Er3+, Yb3+ with cryolite structure

“…Therefore, there is an effective energy transfer between Er 3+ and Yb 3+ , and the up-conversion luminous efficiency of Er 3+ is signicantly improved. [9][10][11][12][13][14][15] The most common way to improve the efficiency of upconversion is to use a host with low phonon energy. 16 We hope to nd materials with suitable crystal eld environment and higher temperature sensitivity around Er 3+ , which can further improve the performance of optical temperature sensor.…”