This article highlights the major role Arthur von Hippel and the Laboratory for Insulation Research at the Massachusetts Institute of Technology played in the early development of the field of ferroelectricity in mixed oxides with the perovskite structure and, in particular, in the identification of ferroelectricity in barium titanate following its discovery in industrial laboratories in the United States during World War II.Very early optical and x-ray studies highlighted the characteristics of the ferroelectric domain structures in both ceramic and single-crystal BaTiO3, the elimination of domains at the Curie temperature TC, and the salient characteristics of the two low-temperature phase transitions. Perhaps the culmination of this work was the detailed studies of lamella 90° domains by Peter Forsbergh and the gorgeous patterns these could generate. This article also traces the manner in which the early studies contributed to whole industries based on perovskite ferroelectrics. The ceramic capacitor industry is now fabricating sophisticated, cofired multilayer capacitors (MLCs) with up to a thousand 1-µm-thick dielectric layers interleaved with base metal electrodes, addressing a market for some 1013 capacitors per year.
Manufacturers of large piezoelectric transducers depend almost exclusively on perovskite-structure oxide ceramics. Navy sonar systems are major customers, but spinoff has occurred into a wide range of commercial and medical ultrasound systems. The capability of current materials has improved more than tenfold over the original BaTiO3 ceramics as a result of the effective application of molecular engineering, a strong testament to the insight of the founder of this area of study.
(Online publication March 31 2011)
Robert E. Newnham is professor emeritus of solid-state science and a former associate director of the Materials Research Laboratory at the Pennsylvania State University. Prior to joining the Penn State faculty, he taught in the Electrical Engineering Department at the Massachusetts Institute of Technology and worked for Arthur von Hippel in the Laboratory for Insulation Research.
Among Newnham's recent awards are the Kingery Award from the American Ceramic Society, the Turnbull Lectureship of the Materials Research Society, the Third Millennium Medal of IEEE, and the Benjamin Franklin Medal in Electrical Engineering from the Franklin Institute. He is also active in several professional societies, having served as editor of the Journal of the American Ceramic Society, secretary of the Materials Research Society, president of the American Crystallographic Association, and Distinguished Lecturer for the IEEE. As a member of the National Academy of Engineering, Newnham has written more than 500 research papers and 20 patents on electroceramics and composite materials for electronic and acoustic applications. His most recent book is Properties of Materials: Anisotropy, Symmetry and Structure, published by Oxford University Press.
Newnham can be reached by e-mail at firstname.lastname@example.org.
L. Eric Cross is an Evan Pugh Professor of electrical engineering at the Pennsylvania State University. He received BS and PhD degrees in physics from Leeds University, where he proceeded to become a University Scholar, assistant professor, and ICI fellow. He was also a senior scientist at the Electrical Research Association (ERA) in England. Cross joined the faculty at the Pennsylvania State University in 1961 as a research associate in ceramics, and later became a senior research associate and professor of solid state science in the Materials Research Laboratory. His research interests are in the field of ferroelectric materials and their applications as dielectrics in capacitors and as piezoelectric and electrostrictive transducers and actuators for medical ultrasound and undersea communication. His work on the phenomenology of ferroelectricity and specifically on the special group of materials known as relaxor ferroelectrics has received international recognition.
Cross is a member of the National Academy of Engineering and a fellow of the American Physical Society, ACerS, the IEEE, and the American Optical Society. He is a member of the Defense Sciences Research Council, which is the senior academic advisory group to the Defense Advanced Research Projects Agency (DARPA). He is also one of the two permanent members of the International Union of Pure and Applied Physics (IUPAP) advisory group on ferroelectricity. He has published more than 650 articles on topics in ferroelectricity and holds some 13 patents.
Cross can be reached by e-mail at email@example.com.