報告人：楊文革

報告題目：Retaining the enhanced properties with pressure-induced lattice and electronic transitions to ambient conditions

報告時間：2025年4月28日（周一）上午10：30

報告地點：分析測試中心100會議室

主辦單位：物理與電子工程學院、科學技術研究院

報告人簡介：

楊文革，1995年畢業于武漢大學物理系，獲理學博士。1995-1997洪堡學者在于利希研究中心合作研究準晶的結果與缺陷。1997-2013 先后在美國卡內基-梅隆大學、橡樹嶺國家實驗室、卡內基研究院做博士后、客座研究員、研究員等職。2024年回國全職加入北京高壓科學研究中心，入選國家級創新人才長期項目，任職研究員至今，2022起擔任北京高壓科學研究中心法人、主任。長期從事材料在極端條件下物質的結構與物性的探索，開發同步輻射在高壓條件下的研究，發表300余篇SCI學術論文。

報告摘要：

Pressure is an effective tool to tune the crystal and electronic structures of materials, which turns out with large property modulation. With a proper kinetical energy phase transition pathway, the tailored properties achieved at high pressure could be retained to ambient pressure for industry applications. Here we want to focus on two systems to demonstrate the great potential for pressure engineered materials with enhanced properties. 1)Transparent conducting oxides (TCO) with high electrical conductivity and high visible light transparency are desired for a wide range of high-impact engineering. Here, we demonstrate the pressure engineering strategy to modulate the lattice and electronic and optical properties on an indium titanium oxides (ITiO) TCO. Strikingly, after compression–decompression treatment on the ITiO, a highly transparent and metastable phase with two orders of magnitude enhancement in conductivity is synthesized from an irreversible phase transition. Moreover, this phase possesses previously unattainable filter efficiency on hazardous blue light up to 600 °C, providing potential for healthcare-related applications with strong thermal stability up to 200 °C. 2) Multiferroic ferroelectric photovoltaic (FPV) materials, which integrate magnetic and ferroelectric properties, are of paramount importance for optoelectronic and photovoltaic applications. We choose the multiferroic material BaFe4O7 with a unique FeO4 tetrahedral and FeO6 octahedral interleaving arrangement. We witness that pressure induces charge transfer from Fe in the tetrahedral sites to Fe in the octahedral sites, leading to charge disproportionation that narrows the bandgap from 2.12 eV to 0.53 eV, positioning it within the optimal range for photovoltaic applications. Simultaneously, pressure-induced polar distortion in the FeO6 octahedron enhances the symmetry breaking of the lattice, resulting in a threefold increase in ferroelectric polarization at pressures between 20-25 GPa. This concurrent modulation of the bandgap and ferroelectric polarization leads to a twofold enhancement in ferroelectric photocurrent. Remarkably, the optimized bandgap (1.42 eV) and enhanced polarization remain stable upon releasing the pressure to ambient conditions. From these two case studies, we present the great potential for enhancing electric, optical, energy harvest performance via pressure-induced electronic structure and crystal structure, offering a promising avenue for the development of high-performance, functional materials.