Volume 30, No. 11
November 2005
Ferroelectricity:
The Foundation of a Field from Form to Function
R.E. Newnham and L. Eric Cross
Abstract
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.
Keywords: Arthur von Hippel, barium titanate, BaTiO3,
capacitors, ferroelectric, interdisciplinary, Massachusetts Institute
of Technology, materials research, MIT,
perovskite, transducers.
|
