Structural phase purification of bulk HfO2:Y through pressure cycling

• 成果类型: Article
• 署名作者: Musfeldt, J. L.; Singh, Sobhit; Fan, Shiyu; Gu, Yanhong; Xu, Xianghan; Cheong, S. -W.; Liu, Z.; Vanderbilt, David; Rabe, Karin M.
• 署名单位: University of Tennessee System; University of Tennessee Knoxville; University of Tennessee System; University of Tennessee Knoxville; University of Rochester; University of Rochester; United States Department of Energy (DOE); Brookhaven National Laboratory; Rutgers University System; Rutgers University New Brunswick; Rutgers University System; Rutgers University New Brunswick; University of Illinois System; University of Illinois Chicago; University of Illinois Chicago Hospital
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14467
• DOI: 10.1073/pnas.2312571121
• 发表日期: 2024-01-30
• 关键词: total-energy calculations; volume changes; calibration; hafnia; gauge

摘要

We combine synchrotron -based infrared absorption and Raman scattering spectroscopies with diamond anvil cell techniques and first -principles calculations to explore the properties of hafnia under compression. We find that pressure drives HfO2:7%Y from the mixed monoclinic (P21/c) + antipolar orthorhombic (Pbca) phase to pure antipolar orthorhombic (Pbca) phase at approximately 6.3 GPa. This transformation is irreversible, meaning that upon release, the material is kinetically trapped in the Pbca metastable state at 300 K. Compression also drives polar orthorhombic (Pca21) hafnia into the tetragonal (P42/nmc) phase, although the latter is not metastable upon release. These results are unified by an analysis of the energy landscape. The fact that pressure allows us to stabilize targeted metastable structures with less Y stabilizer is important to preserving the flat phonon band physics of pure HfO2.