GdNbO 4 :Eu 3+ and LuTaO 4 :Eu 3+ have been successfully prepared with different fluxes (NaCl, KCl, NaCl and KCl) by the molten salt method. X-ray diffraction (XRD) patterns illustrated that well crystallized GdNbO 4 :Eu 3+ and LuTaO 4 :Eu 3+ in the presence of fluxes were formed under reduced temperature (900 °C) in contrast to conventional method (GdNbO 4 :Eu 3+ : around 1200 °C; LuTaO 4 :Eu 3+ : around 1500 °C). Scanning electron microscope (SEM) images revealed that well dispersed particles were achieved (granular or rod-like structures). Meanwhile, the photo-luminescent studies demonstrated that both niobate and tantalate are efficient hosts to sensitize europium red emissions. The results indicated that GdNbO 4 :Eu 3+ using NaCl as the flux gave much enhanced red emission whereas LuTaO 4 :Eu 3+ synthesized with the assistance of mixed salts (NaCl–KCl) achieved the best luminescence.
As candidate thermal/environmental barrier coatings (T/EBCs), the structure characteristics and comprehensive properties of monoclinic-prime (m') RETaO 4 (RE = Yb, Lu, Sc) with excellent Al 2 O 3 /SiO 2 chemical compatibility are studied. Excellent thermal insulation protection will be provided by m'RETaO 4 due to their low thermal conductivity (∼1.6 W m −1 K −1 , 900 °C) and prominent thermal radiation resistance, which is much better than those of YSZ (∼2.5 W m −1 K −1 , 1000 °C) and La 2 Zr 2 O 7 (∼2.0 W m −1 K −1 , 900 °C). The thermal expansion coefficients (TECs) are 3.0–8.0 × 10 -6 K −1 (200−1200 °C), which is suitable for T/EBCs applications. Furthermore, absence of phase transition and extraordinary chemical compatibility with Al 2 O 3 /SiO 2 up to 1500 °C indicate the potential application prospect. The documented governing mechanisms of m'RETaO 4 properties will enable researchers to promote their application in the future investigation.
Mingrui Li,Zhenchuan Hu,Fuyan Su,Ruo Wang,Ruihua Tan,Mei Ding,Piaoyang Wu,Wei Wang
Yb 3+ /Er 3+ -doped up-conversion materials have been widely used in many fields due to high up-conversion efficiency in the visible region. However, it is still challenging to achieve high thermal stability in Yb 3+ /Er 3+ system owing to the non-radiative relaxation. Herein, Er 3+ and Yb 3+ co-doped LuTaO 4 phosphor is synthesized via a high-temperature solid-state method, and we successfully apply the phosphor into ceramic. The integrated emission intensity of the green luminescence could maintain 87.1% of initial intensity at 418 K. Besides, the peaks located at 521 nm and 528 nm achieve anti-thermal-quenching performance, showing an enhancement of 2.28 times and 2.13 times at 418 K, respectively. Based on the optical characterization and fluorescence intensity ratio calculation, a relative sensitivity of 1.432% K −1 at 298 K and an absolute sensitivity of 0.4757% K −1 at 538 K are achieved. In addition, the prepared ceramics also exhibit excellent thermal stability and FIR sensitivity. This work initiates a feasible strategy to accelerate the development of up-conversion luminescent phosphors with excellent thermal stability.
危险品化学品经营许可证（带存储）