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Early Years: Ferroelectric Phase Transitions and Perovskites

A reminiscence of Gen Shirane at the time of his 65th birthday

by B. Chalmers Frazer

We have assembled here today to honor Dr. Gen Shirane in recognition of his many important scientific achievements, and I am very pleased to have been asked to lead off with a few comments on the early years of his career.

Gen's contributions in neutron scattering have been so far reaching and have had such an impact on condensed matter physics that some people, especially among our younger colleagues, may not know that he was already off to a very strong career start before he had ever made use of a neutron.  And indeed when he first picked up the technique of neutron diffraction, it was to bring to bear a powerful new tool in an area of science in which he had already established a strong reputation: ferroelectric structures and phase transitions.

In taking only a brief look back at those early years, I think that we can not only gain anew some appreciation of his accomplishments, but we can also get a good indication of the Shirane that was to emerge later in the mature scientist. In this latter respect, for example, let us look for a moment just at what he had managed to put into print at the time he became Dr. Shirane.

Gen Shirane received his doctorate in physics from the University of Tokyo in 1954.  According to my count, he had published a total of 35 papers up to and by the end of that year. All of these publications were on the physics of ferroelectric crystals, and the high quality of the work had already gained for him an international reputation in this young but rapidly expanding field.  This was impressive output by any standard, but it was especially so if one considers that his previous training was not in physics, but in engineering, and the research was carried out in the aftermath of World War II.

Looking further at these early papers, we find that 27 dealt with members of the famous ABO3 perovskite system; the other 5 involved studies in the other then known systems: KDP, Rochelle Salt and the pyrochlores.  A few months ago, I happened to hear a talk of Gen's in which he jokingly commented on beginning his career with perovskites and now again, almost 40 years later, he has been placing his main research efforts on crystals with perovskite-derived structures, viz. the new high Tc superconductors.  He might also have added, of course, that he had done many important things in between on perovskite-like materials.  Gen has worked on a great variety of other materials also over the years, but one can readily understand why perovskites have been appealing.

With the simple unit cell of the ideal perovskite structure, and considering the rich diversity of physical properties and behavior displayed by the many perovskite-like real materials, this is a particularly attractive system for obtaining research results of generic importance for achieving a basic understanding of phenomena in condensed matter physics.  Some of Gen's early work studying field-induced double hysteresis loops in PbZrO3, as just one example, led to an explanation in terms of the free energy differences between ferroelectric and antiferroelectric phases.  Also, his extensive work on mixed crystal systems and phase diagrams contributed significantly to the understanding of the roles of ionic radii and electronic structure in determining the stability of ferroelectric phases.  The experimental tools used in these and the many other early studies were those for dielectric measurements, x-ray diffraction, preparative materials chemistry, etc. Neutrons were to come later.

I believe that Gen Shirane's first neutron experiment was probably one done about 1955 with me (along with Ray Pepinsky) on the ferroelectric structure of PbTiO3, a crystal in the perovskite system with exceptionally large ionic displacements.  We collaborated from time to time on a number of other neutron experiments over subsequent years.  In looking back on those times when we worked together, my impressions are probably similar to those of others here who have co-authored papers with Gen.  A leading one of these, certainly, is that of his intense and direct involvement in every aspect of an experiment.  He was prepared to vouch for any part of a paper he put his name on as an author.

Gen Shirane has met very high standards over his many years in scientific research, beginning at the earliest stage of his career.  In addition to expressing our recognition of his accomplishments, we also offer our congratulations and best wishes on the occasion of his 65th birthday.

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Last Modified: Wednesday, 26-Jan-2005 16:42:37 EST


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