Speaker: Dr. Alp Sehirlioglu, Case Western Reserve University

Speaker:  Dr. Alp Sehirlioglu, Case Western Reserve University

Title:  Guiding the search for high-temperature ferroelectric perovskites

Abstract:

High temperature ferroelectrics are sought after for actuator applications such as deep well oil drilling, fuel modulation in jet engines or ultrasonic drilling on the surface of Venus. The use of converse piezoelectric effect in actuators require large piezoelectric coefficients to obtain the necessary displacement under a reasonable electric field or within a suitable volume. As a result, of interest are perovskite ferroelectrics near a morphotropic phase boundary at which the electromechanical properties maximize. However, the operating temperature of such materials have been limited by phase transition temperatures, increased ac conductivity at elevated temperatures, and depoling temperature. This talk will exemplify different approaches to discovery of new high temperature ferroelectrics, varying from trial and error to intuition or theory driven to approaches enabled by information sciences. Advantages and disadvantages of all the approaches will be discussed. The focus will be on the solid solutions of Bi-containing perovskites with PbTiO3. Initially, the tolerance factor of the unit cell and the ferroelectric activity of the cations were introduced as guidelines in designing compositions. Since then, these material systems became more complicated with solid solutions as ternaries or quaternary systems, as well as with aliovalent dopants and through microstructural engineering. The traditional approach of trial and error, even with some guidelines, cannot address the associated search space. A two-step machine learning approach will be discussed to guide experiments in search of this unexplored perovskite space for discovery of new materials with high Curie temperature. Effects of processing conditions will also be introduced related to their effects on the final performance of the piezoceramics.

Bio:

Alp Sehirlioglu is an Associate Professor at the Department of Materials Science and Engineering, Case
Western Reserve University. He received his B.S. in Materials Science and Metallurgical Engineering
from Middle East Technical University, (Ankara, Turkey), M.S. in Ceramic Engineering from Alfred
University, (Alfred, NY) and Ph.D. under Prof. David Payne in Materials Science and Engineering from
University of Illinois at Urbana Champaign (Urbana, IL). His research is on control and application of
interfaces (including surfaces) has two foci: (1) Interfacial control of bulk behavior and (2) 2D behavior.
All of his research topics are united under oxide based functional ceramics. He is an Associate Editor of
the Journal of the American Ceramic Society and the chair of Electronics Division at the American
Ceramic Society. He is also the chair of the Diversity and Inclusion Standing Committee at IEEE-UFFC,
where he is senior member serving in Ferroelectrics Committee. He received NSF CAREER Award,
AFOSR Young Investigator Program (YIP) Award, Young Alumnus Award from the Department of
Materials Science and Engineering at University of Illinois at Urbana Champaign (UIUC), Case School of
Engineering Research Award and Charles F. Lucks Award, by International Thermal Conductivity
Conference, Inc., as well as two NASA Special Achievement Team Awards for “PPU Capacitor Failure
Investigation Team” and “Thermoelectrics Team”. Outside of his research, Alp has been working on the
use and study of Augmented Reality (AR) as a new pedagogical tool in collaboration with cognitive space for

discovery of new materials with high Curie temperature. Effects of processing conditions will also be introduced related to their effects on the final performance of the piezoceramics.