東北大学 · 材料科学
Zeyu Lyu教授の研究室は、赤外線発光材料の開発に注力しており、特にCr³⁺やBi³⁺ドープ蛍光体を用いた高効率・高耐熱性の発光材料の設計を主な研究テーマとしています。Crystal-field工学やトラップ工学を応用した構造制御により、発光色の精密調整と熱的安定性の向上を実現しています。また、NIR-LEDや光学温度計への応用を視野に入れた、応用指向の材料創出が特徴です。
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Near-infrared (NIR) luminescent materials have attracted enormous attention for the cutting-edge applications in optical thermometer and NIR LEDs. Herein, we report a highly efficient Cr3+-doped NIR phosphor, BaAl4Sb2O12:0.024Cr3+ (BASO:Cr3+), with 91% internal quantum efficiency. Strikingly, BASO:Cr3+ possesses rare and typical Stokes/anti-Stokes phonon sidebands. The Stokes phonon sideband decreases with increasing temperature, while the anti-Stokes one increases considerably. Consequently, th
Abstract Crystal‐field engineering can obtain targeted emission more effectively, compared with the laborious experimental screening of new hosts. However, there still lack of paradigms for obtaining Ce 3+ ‐doped cyan phosphors by crystal‐field engineering, and the correlation between the emission and the local structure of the Ce 3+ ions has rarely been disclosed. Herein, through substituting the K + in K 3‐y Rb y GdSi 2 O 7 :Ce 3+ with Rb + , the emission color changes from yellow‐green to cya
Trap engineering is widely applied to contend with thermal quenching of phosphors. However, the incidental detriment of the luminescent efficiency has long been neglected. Herein, we propose a paradigm for achieving a high-performing Bi3+-doped phosphor with moderate trap engineering. Through introducing appropriate traps in a neutral atmosphere and proper doping concentration, we have successfully created a novel Ba2GdAlO5:Bi3+ yellow phosphor that exhibits exceptional thermal stability (104.1%
Abstract Near‐infrared (NIR) phosphors converted light‐emitting diodes (NIR pc‐LEDs) are ideal NIR sources for versatile applications, which imply the practical significance in tailoring the emission of the NIR phosphors to enhance the performance for specific application. Herein, a paradigm of tailoring the emissions in a series of Cr 3+ ‐doped phosphors to match the applications in NIR lighting, detection, and short‐wave infrared sources through combinatorial management of crystal‐field and en
Polarized emission, an inherent characteristic that correlated with structure and morphology, is very sensitive to orientation. For the upconversion (UC) emission of lanthanides, the mechanism of polarization is rarely discussed, and the highly polarized UC emissions are poorly developed. Herein, with the benefit of the strong anisotropic crystal field, well-resolved emissions from lanthanide-doped LiYF<sub>4</sub> crystals were studied, and highly polarized UC emissions from Er<sup>3+</sup> and
This study focuses on news content related to China and COVID-19 during the COVID-19 pandemic and investigates how media frame, affected the emergence of anti-China sentiments through a case study of Japanese online news discourse. We collected large-scale digital trace data including online news and comments during the COVID-19 pandemic. By employing deep learning-based sentiment classifications, we were able to measure the extent of anti-China sentiments expressed through comments during the p
The NIR phosphor Sr 3 SiAl 10 O 20 , which realizes ultra-broadband emission via dual energy transfer within two Cr 3+ emitters and Cr 3+ → Yb 3+ , can be used for NIR pc-LEDs, showing great potential in the fields of night-vision illumination, nondestructive surveillance, and information encryption.
For Tb<sup>3+</sup>-doped green phosphors, the energy transfer from Ce<sup>3+</sup> to Tb<sup>3+</sup> can largely enhance the absorption of excitation; however, obtaining phosphors that exhibit both high quantum efficiency and thermal stability continues to pose a significant challenge. Herein, we established a paradigm to achieve novel silicate BaY<sub>4</sub>Si<sub>5</sub>O<sub>17</sub> (BYSO):Ce<sup>3+</sup>,Tb<sup>3+</sup>. The near-ultraviolet light efficiently excites the BYSO:Ce<sup>3+</
Phase transition of the polymorphs is critical for controlled synthesis and property modulation of functional materials. Upconversion emissions from an efficient hexagonal sodium rare-earth (RE) fluoride compound, β-NaREF<sub>4</sub>, which is generally obtained from the phase transition of the cubic (α-) phase counterpart, are attractive for photonic applications. However, the investigation of the α → β phase transition of NaREF<sub>4</sub> and its effect on the composition and architecture is
Although there have been numerous reports on broadband near-infrared (NIR) emitting phosphors, their emissions are mainly concentrated in the range of 700-1000 nm (NIR-I). Herein, we successfully synthesized a broadband near-infrared phosphor CaMgGeO<sub>4</sub>:Cr<sup>4+</sup>(CMG:Cr<sup>4+</sup>) with an emission in the range of 1000-1600 nm (NIR-II). The introduction of Er<sup>3+</sup> ions into CMG:Cr<sup>4+</sup> resulted in a wider near-infrared emission phosphor CaMgGeO<sub>4</sub>:Cr<sup
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