Clive A. Randall is a Distinguished Professor of Materials Science and Engineering and has served as the Director of Materials Research Institute at The Pennsylvania State University, University Park, Pennsylvania, USA, since 2014 (https://www.mri.psu.edu/). He was Director for the Center for Dielectric Studies between 1997 and 2013, and in 2013 formed a new Center as Co-Director, the Center for Dielectrics and Piezoelectrics, for which he still serves as Technical Advisor since 2016. Prof. Randall received a B.Sc. with Honors in Physics in 1983 from the University of East Anglia, and a Ph.D. in Experimental Physics from the University of Essex in 1987, both in the United Kingdom. He has authored/co-authored over 500 technical papers, with over 22,000 citations and an h-factor of 77. He also holds 15 patents (with 2 pending) in the field of electroceramics. Prof. Randall’s research interests are in the area of discovery and compositional design of functional materials for electrical energy transduction and storage, defect chemistry and crystal chemistry and their impact on phase transition behavior, electromechanical devices based upon electrostriction and piezoelectrics, supercapacitors, thermoelectrics, and microwave materials. He has used a variety of different processing and characterization methods that have impacted manufacturing and development processes for materials, particularly in the capacitor and piezoelectric industry. His research group has been supported from a number of different sources, including the National Science Foundation, the U.S. Air Force Office of Scientific Research, U.S. Department of Energy, the Office of Naval Research, the U.S.-Israel Binational Scientific Foundation, NASA, and substantial funding from the private sector. Professor Randall was honored with the American Ceramic Society Fulrath Award in 2002; the Wilson Research Award from the College of Earth and Mineral Sciences, Penn State University, in 2003; he spent one year (2004–2005) as a Visiting Fellow of Fitzwilliam College, University of Cambridge, U.K.; he was elected Fellow of the American Ceramic Society in 2005 and Academician of the World Academy of Ceramics in 2006; in 2007, he and his colleagues received the R&D 100 Award for their Integrated Fiber Alignment Package (IFAP); he received the Spriggs Phase Equilibria Award in 2008; in 2009, he received the University Scholar Award (Engineering) from Penn State University; he received the Japanese FMA International Award; he gave the Friedberg Lecture at the American Ceramic Society, both in 2011; in 2013, he received, along with his student, the Edward C. Henry Best Paper of the Year from the American Ceramics Society Electronics Division; he received the IEEE UFFC-S Ferroelectrics Recognition Award (2014); he was the IEEE distinguished lecturer (2019) and he received the Electroceramic Bridge Building Award at the 17th US-Japan Seminar on Dielectric and Piezoelectric Ceramics (2015); he was inducted in 2019 as an honorary fellow of the European Ceramic Society.
Professor Randall utilizes a combination of the material science approaches of structural-property-process-performance relations and coupling these with material physics to understand, design, and manufacture future generation electroceramic materials and devices. Specific materials the group is studying are ferroelectric and related materials, microwave, and piezoelectric materials in a variety of different forms, ranging from crystal structure, composition, particle and grain size, bulk, film and composites are considered.
His philosophy is to use extreme application needs to direct a fundamental study to enable material advances to be made and implemented. These extreme performance parameters include a combination of temperature, electric field strength, and frequency-, time-, and size-reduction. Under these conditions, we are concerned with basic mechanisms that control the nature of properties under all times of use. In particular, the time dependent failure mechanisms may be controlled through important physical processes, such as electron injection at an electrode or grain boundary, oxygen vacancy migration, defect dipole rotations, and thermochemical and electrochemical reactions at interfaces. Any of these or similar phenomena are built into a material through the fabrication thermal processes and remain in a metastable state, but ultimately these defects drive the degradation mechanisms and thereby prevent the implementation of new materials into a system. Once understanding the sources and failure processes, the group develops methods through process modifications or design new materials or chemistries to suppress these deleterious effects. To determine these phenomena the group embraces state-of-the-art transmission electron microscopy techniques to determine spatial details of non-stoichiometry, and these are coupled with determined time and frequency domain electrical characterization analytics.
Over the years, the Randall group has always explored novel processing methods to design materials and composites. This ranges from using fast firing and atmospheric conditions to managing opportunities in kinetics and thermochemical properties. This has also included use of directed particulate assembly methods using electric fields to force particles into spatial control via electrophoretic deposition and dielectrophoretic assembly. Electric fields and pulse poling strategies have also been considered for designing optimized ferroelectric domains configurations via controlling nucleation and growth kinetics under the poling of single crystal relaxor ferroelectrics. Furthermore, we are investigating novel processing techniques to substantially reduce the energy required for fabricating ceramics and ceramic-polymer composites. They have recently introduced a new technique, which has been termed Cold Sintering Process, enabling the densification of many materials at temperatures between 100°C to 300°C, a major paradigm shift in the strategic thinking of sintering. These temperatures enable co-sintering of ceramic materials, polymers, and metals, allowing a unique universal processing strategy to develop unique composites and new functionalities involving all material classes, presently being considered at various TRL’s. There are multiple wins with reconsidering thermal processes in materials fabrication: there is the environmental and energy sustainability advantages; there is the ability to design unique combinations of materials not previously possible; and there are fast and lower cost possibilities in manufacturing advanced materials and devices.
Technology Impacted by Research:
Many of the major manufacturers of multilayer ceramic capacitors use fast firing approaches to control the production of the most advanced devices. Randall and collaborators used kinetics to limit deleterious interface reactions between high surface area nickel electrode materials, the high surface area BaTiO3 powders, and residual carbonaceous phases resulting from incomplete debinding in multilayer ceramic capacitors. The early work for this came from Randall’s efforts in the Center for Dielectric Studies and allowed dielectric layers to increase in numbers and in thickness, to substantially increase the capacitive volumetric efficiency. Randall’s group still works very closely with all the leading multilayer ceramic capacitor companies. Further impact in this industry has been in the form of developing measurement techniques that have now been introduced as quality control methods for the production and screening of highly reliable capacitive devices. Also, new compositions, materials, and dopant strategies have also been implemented into several dielectric and piezoelectric materials based on work from the group. This group is also actively working with many companies across different ceramic and ceramic polymer technologies to rapidly accelerate the adoption of cold sintering into an industrial scale.