Resolving the dynamic correlated disorder in KTa1-XNbXO3

• 成果类型: Article
• 署名作者: He, Xing; Gupta, Mayanak K.; Abernathy, Douglas L.; Granroth, Garrett E.; Ye, Feng; Winn, Barry L.; Boatner, Lynn; Delaire, Olivier
• 署名单位: Duke University; Bhabha Atomic Research Center (BARC); United States Department of Energy (DOE); Oak Ridge National Laboratory; United States Department of Energy (DOE); Oak Ridge National Laboratory; Duke University; Duke University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10833
• DOI: 10.1073/pnas.2419159122
• 发表日期: 2025-02-18
• 关键词: total-energy calculations; phase-transitions; neutron-scattering; thermal-conductivity; phonon-scattering; knbo3; STABILITY; ktao3; ktn; dispersion

摘要

Understanding the complex temporal and spatial correlations of ions in disordered perovskite oxides is critical to rationalize their functional properties. Here, we provide insights into the longstanding controversy regarding the off-centering of transition metal (TM) ions in the archetypal ferroelectric alloy KTa1-xNbxO3 (KTN). By mapping the full energy (E) and wavevector (Q) dependence of the dynamical structure factor S(Q, E) using neutron scattering, and rationalizing our observations with atomistic simulations leveraging machine learning, we fully resolve the static vs dynamic nature of diffuse scattering sheets, as well as their composition (x) and temperature dependence. Our first-principles simulations, extended with machine- learning molecular dynamics, reproduce both inelastic neutron spectra and diffuse features, and establish how dynamically correlated TM off-centerings couple to phonons, unifying local and collective viewpoints. This study sheds light into an exemplary ferroelectric system and shows the importance of mapping the full S(Q, E) to reveal critical spatiotemporal correlations of atomic disorder from which functional properties emerge.