Emergent Materials under Extremes and Decisive In Situ Characterizations: Pressure-induced dramatic changes in structures and properties
Sponsored by: ACerS Basic Science Division
Program Organizers: Xiaofeng Guo, Washington State University; Xujie Lu, Center for High Pressure Science & Technology Advanced Research; Hua Zhou, Argonne National Laboratory; Judith Driscoll, University of Cambridge; Hongwu Xu, Los Alamos National Laboratory

Wednesday 8:00 AM
November 4, 2020
Room: Virtual Meeting Room 36
Location: MS&T Virtual

Session Chair: Xujie Lü, Center for High Pressure Science & Technology Advanced Research; Hua Zhou, Argonne National Laboratory


8:00 AM  
Evolution of Structure, Electrical, and Optical Properties in Ti-doped In2O3 Nanocrystals under Pressure: Xuqiang Liu1; Yandong Wang2; Wenge Yang3; 1Northeastern University(China) and HPSTAR; 2Northeastern University; 3Center for High Pressure Science & Technology Advanced Research(HPSTAR)
    Metal-doped In2O3 oxides have been widely used in transparent conductive devices with their excellent electrical and optical properties. Improving conductivity would promote huge industrial market for advanced applications. Here we report our systematical investigations of the Ti-doped In2O3 on the crystalline structure, electric conductivity and optical band gap under high pressure and the excellent promotion on the properties after pressure treatment. The Ti-doped In2O3 nanocrystals undergoes a structural phase transition (b-TIO to c-TIO) beyond 17.5 GPa, and the high pressure c-TIO phase can be quenched to ambient conditions. The pressure treated c-TIO shows two orders of magnitude enhancement in electric conductivity without much degradation on the optical transparency. These findings not only help us to understand the pressure effects on the crystalline structure, electrical and optical properties of metal-doped Ti-doped In2O3 oxides under extreme conditions but also provide a practical route to synthesize new transparent conductive materials with better performance.

8:20 AM  Invited
Giant Pressure-induced Enhancements in Electronic Transport and Photoelectric Properties in 2D and 3D Structures: Wenge Yang1; 1Center for High Pressure Science and Technology Advanced Research
    Layered chalcogenides have been considered as excellent candidates for superconductor and thermoelectricity applications. The pressure-driven 2D–3D structural reconstruction is an efficient strategy for tuning the electronic configuration and optical properties. With aids of in situ structural, optical and electronic characterizations, we uncovered the giant enhancements in the electronic transport and phototelectric properties with the pressure tuning effect on this layered materials. Comparing the pressure induced structure phase transition in many 3D materials, the pressure-driven buckling effect on the layered bismuth oxysulfide Bi9O7.5S6 is significent. Under pressure, the layer and bonding distances between and within BiO and BiS layer change dramatically, which drives the enhancements of electric conductivity by 6 orders of magnitude, increasing of photocurrent by 4 orders of magnitude, and significant narrowing down of band gap from 1.34 to 0.45 eV. These findings may open up a new avenue for discovering and designing high-efficiency photodetectors and energy-harvesting materials.

8:50 AM  
High Pressure & Temperature Investigation into Thorium Orthosilicates: Andrew Strzelecki1; Jason Baker2; Stella Chariton3; Vitali Prakapenka3; Hongwu Xu2; Mostafa Ahmadzadeh1; John McCloy1; Paul Estevenon4; Adel Mesbah4; Nicolas Dacheux4; Xiaofeng Guo1; 1Washington State University; 2Los Alamos National Laboratory; 3Argonne National Laboratory; 4ICSM
    The thorium orthosilicate minerals, thorite and huttonite, are isochemical (ThSiO4), but differ in crystal structure. Thorite is isostructural to zircon which is tetragonal and belongs to the I41/amd space group. Huttonite, the high temperature polymorph, is isostructural to monazite being monoclinic and crystallizes into the P21/n space group. Other tetravalent metal orthosilicate, such as ZrSiO4, HfSiO4, and USiO4 are known to exhibit a pressure induced phase transition from the zircon structure to scheelite structure (I41/a). However, ThSiO4 may not have such a transition indicated previously by computational work. The huttonite phase has only been investigated experimentally under elevated temperature conditions. In this presentation we will highlight the first ever experimental work into the pressure induced phase change of thorium orthosilicates utilizing both synchrotron powder x-ray diffraction and Raman spectroscopy. In situ high pressure and high temperature was generated by combination of diamond anvil cells and laser heating.