Description:

The Department of Materials Science and Engineering welcomes you to its 2016 Winter Colloquium Series.

Juan Claudio Nino
Location: Tech L361, 4:00pm

"Colossal Effective Permittivity in Ceramics: A Story of Defects”
In the last decades, colossal effective permittivity (CEP, εr > 104-5) has been reported in a number of electronic ceramics. To date, there are several oxide systems that exhibit this phenomenon. Examples include, CaCu3Ti4O12 (CCTO), BaTiO3, K0.3MoO3, Bi1-xLaxNiO3, and more recently co-doped TiO2. In this colloquium presentation, the phenomenon of colossal effective permittivity will be reviewed by focusing on a few of these compounds, to describe our current understanding on the different mechanisms responsible for the observed permittivity (i.e. surface barrier-, grain boundary-, internal barrier-layer capacitor, polaron hopping, etc.). Moreover, recognizing that CEP, is primarily the result of extrinsic and “quenched” intrinsic defects, the effects of composition (precursors, dopants, impurities, etc.), processing (fast firing, reducing atmosphere, etc), and sample preparation (polishing, electroding, annealing) will also be discussed. Further, an attempt to summarize best practices in terms of dielectric characterization that most accurately allow the investigation of the nature of CEP will be made in order to provide a common ground for future research in the field. Finally, an overview of the potential electronics application space for CEP materials will be discussed.

Biography:
Dr. Juan Claudio Nino, is a Professor in the Materials Science and Engineering Department at University of Florida (UF) in Gainesville, FL. He obtained his bachelor’s degree in Mechanical Engineering in 1997 at Los Andes University (Bogotá, COLOMBIA). He was a Lecturer at the Colombian Engineering School before joining The Pennsylvania State University in 1998, where he completed his doctoral degree in Materials Science and Engineering in 2002. After a postdoctoral appointment focusing on ferroelectric thin films at the Materials Research Institute (State College, PA), he joined UF in Fall 2003 as an Assistant Professor. Since, he has established the Nino Research Group (NRG) with main focus of the investigation of fundamental relationships governing energy-related materials towards enhancing their efficiency, performance, and sustainability. NRG’s research investigates ceramics, polymers, bio-inspired materials, and their composites. With over 100 publications in the field and four patents, current research focus includes optimization and development of materials for: (a) electrolytes and cathodes for ionic and protonic conduction devices, (b) high frequency and high temperature dielectrics, ferroelectrics and piezoelectrics, (c) porous ceramics and composite foams, and (d) semiconductors and scintillators for radiation detection. He is a recipient of the CAREER award by the US National Science Foundation. In 2009 he received the J Bruce Wagner Jr Young Investigator Award from the Electrochemical Society. In 2014 he received the Fulbright US Scholar Innovation and Technology Award from the US Department of State. He is an Associate Editor for the Journal of the American Ceramics Society, and a Coordinating Editor for the Journal of Electroceramics.