LSO — Ideal optical pressure sensor - Dr. Wenge Yang

JULY 11, 2017

A material with good structural stability, chemical durability, and radiation tolerance under extreme conditions is necessary and long challenge for developing new pressure sensors. New work co-led by HPSTAR scientist, Dr. Wenge Yang found novel visble photoluminescence in pyrochlore La2Sn2O7 induced bypressure. This unexpected reversible photoluminescence suggests that La₂Sn₂O₇ might be an ideal optical pressure-sensor under extreme conditions. The results are published on Advanced Materials.

Pyrochlore La2Sn2O7 (LSO) has potential applications in light emitting, disposing of high-level radioactive waste in safe geologic repositories under extreme condition due to its extraordinary chemical stability, and excellent radiation tolerance etc.

In addition, LSO is simultaneously transparent to visible light and well conducting electricity. There is very rare of this kind of materials.

Pyrochlore LSO shows a strong near-infrared fluorescence at ambient pressure. And the team’s previous work has shown that pressure induced photoluminescence (PL) change in pyrochlore Eu2Sn2O7.

“Pressure has show powerful effect in tuning physical properties and discovering new phenomenon, which guides people for advanced materials discovery”, said Dr. Wenge Yang.

“These inspired us to further characterize the high-pressure PL phenomenon of pyrochlore LSO”, added Dr. Wenge Yang.

When subjects to compression, LSO shows visible PL above 2 gigapascals. PL spectrum intensity shows obvious change with pressure. What’s more, the PL peak shifts with pressure.

“These are similar with what happens in Ruby, a pressure calibrate under extreme conditions”, said Yongsheng Zhao, a PhD student in Dr. Wenge Yang’s group and who led the research.

More importantly, the pressure induced visible photoluminescence will disappear with pressure reduced to ambient conditions, which means the pressure induced PL is reversible.

“This reversible visible PL dependent on pressure suggests that LSO may provide a great calibration tool for pressure sense at extreme conditions”, Dr. Wenge Yang added.

With the aim of unraveling the mechanism behind the pressure induced PL effect, the researchers conducted detailed analyses of the high-pressure crystal/electronic structures of LSO.

In-situ high pressure X-ray diffraction and resistance measurements show that the anomalous PL behavior was associated with lattice distortion by phase decomposition and novel visible PL was associated with semiconductor-insulator transition.

“Pressure induced and enhanced visible PL would lead fundamental understanding and open up new applications of new PL materials under pressure. All these bring us a new sight for nuclear-waste host materials”, said Dr. Wenge Yang.

Caption: Pressure‐induced novel visible PL in LSO.

Media report:

知社学术圈：https://mp.weixin.qq.com/s/NGAOLJtQ6du2g8PoHgw1qg

锡酸盐烧绿石La₂Sn₂O₇是一种透明导电氧化物，是潜在的薄膜器件材料如发光二极管和电致发光平板显示器等。在室温常压条件下，La₂Sn₂O₇不具备电子跃迁导致的发光特性。北京高压科学研究中心的杨文革研究员与吉林大学的王欣教授合作的研究小组在锡酸盐烧绿石La₂Sn₂O₇中观测到了强的室温常压近红外荧光光谱，在高压下发现了压致发光特性，而且这种压致发光是可逆的。他们提出烧绿石La₂Sn₂O₇新颖的可逆压致发光特性、稳定的化学性质和强的抗辐射能力，将会深海极端环境下工作的光压力传感器材料。