报告题目：Frequency-dependent ferroelectric behaviour of BaMn3Ti4O14.25 at room temperature
报告人：Professor Jackie Li
单位：City College of New York (CCNY)，USA
时间：2016年7月20日14:00-15:30
地点：综合实验一号楼602
Report Abstract:
Professor Jackie Li report activation field and selective frequency-dependent ferroelectric behavior of BaMn3Ti4O14.25 at room temperature. BaMn3Ti4O14.25 (BMT-134), a recently discovered multiferroic complex oxide, exhibits antiferromagnetic and ferroelectric behavior, and belongs to the hollandite crystal class. The microstructure can be manipulated through processing conditions to prepare a nanocrystalline textured tablet. Under an electric field loading condition, a clear hysteresis loop of the electric field-displacement curve is obtained at 50 Hz, indicating room temperature ferroelectricity is attainable under the right processing conditions. When the frequency is increased to 500 Hz, the coercive field also increases, until the frequency reaches 5 kHz, at which point the electric field versus electric displacement becomes linear indicating the difficulty of domain switch at high frequency. Then, a micromechanics based model is adopted to evaluate the ferroelectric hysteresis behavior of the new material. The predicted results showed reasonable agreements with experiments for a wide range of frequency.
Professor Jackie Li Introduction：
Jackie Li is a Professor of Mechanical Engineering at the City College of New York (CCNY). Her research interests include micromechanics, nano-mechanics, nonlinear and time-dependent mechanical properties of composites, nonlinear electro-mechanical coupling behavior of ferroelectrics, mechanicalpropertiesof nanotubes and nanotube-reinforced composites, nanocrystalline materials, and self-sensing of carbon-reinforced composites. She is a recipient of NSF Career award for her research and education on ferroelectric materials. She was also one of invited participants in the National Academy of Engineering’s annual Symposium on Frontiers of Engineering, which brings together outstanding leaders and top-notch people from disparate fields in engineering and challenges them to think about the developments at the frontiers of areas different from their own. Her current research activities are on electric and mechanical behavior of carbon nanotubes and CNT-reinforced composites, electro-mechanical coupling behavior of ferroelectrics and nano-ferroelectrics, nanodielectric composites for energy storage applications, and multiferroics. She has over 20 years research experiences in the fields. Prof. Li received her BS degree in Mechanics from Peking University in 1986, M.Eng. degree in Applied Mechanics from BIT in 1989, and Ph.D. degree in Mechanical and Aerospace Engineering from Rutgers University in 1995. Prior to her appointment at CCNY in 2002, she was an Assistant Professor at The Cooper Union for four years.
