清华大学材料科学与工程研究院《材料科学论坛》学术报告
报告时间：2026年4月22日上午10:00-11:30
报告人：Dragan Damjanovic教授（瑞士洛桑联邦理工色播app
）
报告地点：清华大学逸夫技术科学楼A205学术报告厅
邀请人：王轲老师
报告题目：Meaning and Importance of Nonlinear Behavior and Measurements
报告摘要：
In this talk, the need to study nonlinear properties in ferroelectrics is illustrated using materials like PZT and BaTiO₃, which exhibit nonlinear piezoelectric and dielectric responses even under weak to moderate fields. Such nonlinearity, often accompanied by hysteresis, is generally undesirable for applications and motivates understanding its origin.
Nonlinear behavior primarily arises from reversible and irreversible domain wall motion. Studying nonlinearity (or its absence) therefore provides insight into domain wall processes and how they are affected by factors such as chemistry, structure, and microstructure.
A simple random-potential model, adapted from ferromagnetics, qualitatively and quantitatively describes domain wall contributions in soft PZT via harmonic analysis. This model fails for hard PZT, but comparing soft and hard materials reveals microscopic mechanisms of extrinsic response.
The approach is extended to relaxor ferroelectrics, addressing longstanding questions while noting limitations. Finally, methods for measuring weak-field nonlinear strain and polarization are discussed, along with experimental challenges, data interpretation pitfalls, and the potential extension to other materials.
报告人简介：
Dragan Damjanovic earned a BSc diploma in Physics from the Faculty of Natural Sciences and Mathematics at the University of Sarajevo in 1980 and a PhD in Ceramics Science from the Department of Materials Science and Engineering at the College of Earth and Mineral Sciences, Pennsylvania State University (PSU) in 1987.From 1988 to 1991, he worked as a research associate at the Materials Research Laboratory at PSU. In 1991, he joined the Ceramics Laboratory in the Department of Materials Science and Engineering at École Polytechnique Fédérale de Lausanne (EPFL). During his time there, he led the Group for Ferroelectrics and Functional Oxides at the Institute of Materials, and taught undergraduate and graduate courses on the structure and electrical properties of materials. His research focused on fundamental and applied investigations of the piezoelectric, ferroelectric, and dielectric properties of a wide range of materials. He retired from EPFL in March 2022.