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生嶋明教授和石橋善弘教授学术报告
发布日期:2016/11/16

报告人及报告题目:

  生嶋明教授-An Invitation to The Quantum World

  石橋善弘教授-The Morphotropic Phase Boundary as a Guide in Search for

  Functional Ferroelectric Materials

报告时间:2016年11月16日(周三)

报告地点:图书信息楼8楼报告厅

邀请人:平野真一

报告人简介:

  石橋善弘-名古屋大学著名教授;

  生嶋明-丰田技术协会管理顾问。

报告简介:

All of phenomena observed in the universe are well understood by the quantum mechanical concept however large or small the scale of the phenomenon is. Firstly, the necessity of the quantum concept is introduced. Being based on the concept or understanding, it will be shown that any particle systems can be classified into only two types; the Boson (Bose particle) and the Fermion (Fermi particle) systems. And, it will be explained what we observe in macroscopic scale where we live are just the classical limit of quantum world.Two typical quantum mechanical phenomena, the superconductivity and the superfluidity, will then be introduced. These two very dramatic phenomena can only be observed at sufficiently low temperatures, sufficiently enough that typical energies to govern these phenomena become well greater than the thermal energy or the thermal disturbance given by the product of the Boltzmann constant and the absolute temperature. These two phenomena are seemingly very different from each other. However, physical understandings are quite the same that the effects come from the Bose-Einstein condensation of Boson system. Some typical examples of the superconductivity and the superfluidity ever observed during the last 100 years will be shown. (An Invitation to The Quantum World-生嶋明教授)

Some of the perovskite-type oxide ferroelectrics like PZT (the mixed crystals of PbTiO3 and PbZrO3), sitting in the vicinity of the morphotropic phase boundary (MPB), are known to show excellent physical properties, so can be useful functional materials for actuators, sensors etc. It used to be interpreted, for many years, that such excellent properties are given rise to by the coexistence of two phases sitting at both sides of MPB. Nowadays, however, it is believed that these properties are obtainable in principle even in a single phase.To show it, the Landau theory of structural phase transitions is applied.  Based upon the phase diagram including MPB reproduced with the Landau thermodynamic potential, it is clarified that the usefulness of PZT, i.e., the colossal dielectric, elastic and electro-mechanical responses are all attributable to a special feature of the thermodynamic potential, which is almost isotropic in the vicinity of MPB in the order parameter space, so is very flat along the direction perpendicular to the spontaneous polarization.(The Morphotropic Phase Boundary as a Guide in Search for Functional Ferroelectric Materials-石橋善弘教授)

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