MSE 298 Seminar Lecture (Zoom): The Digitization of Materials and Investigators

Via Zoom Meeting ID: 995 8022 3426 Password: 587901

Abstract: In this talk, three different studies will be highlighted. With the first, we will discuss how to increase the energy density of high dielectric constant capacitors. Results from experiments and simulations performed on a high-energy density polymer-matrix hybrid composite, which features ferroelectric barium titanate nanoparticles and multi-walled carbon nanotubes (MWCNT), embedded in poly (vinylidene fluoride) (PVDF) provide important findings. The addition of the conductive MWCNT increases the charge storage ability of the matrix polymer by serving as a polarized charge transport phase for the ferroelectric nanoparticles. The second example will illustrate the importance of controlling the 3D arrangement of a second phase for achieving the electrical properties desired for EMI shielding or contact electrodes while minimizing cost. MWCNT/PMMA composites were fabricated using three different mixing methods (mechanical, solution and melt mixing), which creates different arrangements of the carbon nanotubes that result in very different electrical properties. The third study will show the interesting microstructure that sol-gel-processed ITO thin films form during layered deposition. ITO films are ubiquitous in many optoelectronic applications because of their unique combination of high transparency and high electrical conductivity. Our goal was to develop a patternable method of deposition that could be used for flexible electronics without requiring material waste.

Bio: The Gerhardt group has worked with ceramic and polymer matrix composites for more than 20 years and has more recently focused on conducting ceramic oxides and ferrimagnetic compositions. One of the main hallmarks of the research is that they utilize extensive analysis of the ac properties of the materials they fabricate (e.g., electrical conductivity, dielectric properties, percolation threshold, effect of size, shape and distribution of the secondary phase, etc.). This analysis is then used to predict structure-processing-property relationships in a quantitative way. In addition to electrical phenomena, they also focus on microstructural characterization of their materials using optical microscopy, SEM, TEM and AFM, combined with numerical simulations, optical spectroscopy as well as X-ray and neutron scattering experiments. Gerhardt collaborates with researchers at various national labs including Oak Ridge and Argonne National Labs. She has been a faculty member at the Georgia Institute of Technology since January 1991. She was elevated to professor in 2001 and chosen as the Senior Goizueta Faculty Chair in 2015. Gerhardt is the director of the Electrical Testing of Materials and Devices Center, which conducts detailed experiments on all classes of materials as a function of frequency, temperature, voltage and atmosphere. Her group has done work for Arnold Magnetics, NanoResearch, Sandia National Laboratories and others and has assisted many research groups at Georgia Tech. In addition to the composite materials described above, her group also conducts research on the fabrication and characterization of thin films such as ITO and carbon nanotube thin films and relates their nanostructure to the obtained electrical and optical properties. She is the author of over 200 peer-reviewed publications and a member of MRS, IEEE, ACerS, Sigma Xi and other professional organizations.