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Proceedings Paper

Does BaTi03 lose the center of symmetry in a single step on the cubic-to-tetragonal transition? A new finding by the milli-Kelvin-stabilized cell"
Author(s): Akira Kojima; Yukio Yoshimura; Hiroshi Iwasaki
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Paper Abstract

We have developed mK-stabilized cell having a fine temperature stability better than 1 mK which can be used to investigate phase transitions in solids not only by making calorimetric measurements but also, with the heat flux sensor, by making other kinds of measurements at an extremely slow rate of temperature change both on heating and cooling. Precise data with a very fine temperature resolution can be obtained by the measurements. It was applied to the measurements for the cubic-to- tetragonal transition at 408 K in BaTiO3. A single crystal sample prepared by the top-seeded solution growth method was used and no external field was applied across the sample previously. Dielectric constant and displacement currents were measured as well as calorimetric properties. It was found that BaTiO3 does not undergo the transition in a single step on cooling but in a multi-step with several thermal anomalies in a temperature range of 0.5 K. The first step corresponds to the process with a large change of dielectric constant but without any displacement currents, while the last step is accompanied by the displacement currents with an appreciably small dielectric change. Flow of the displacement currents implies the loss of the center- of-symmetry. The results obtained may cast light into the elucidation of the transition process.

Paper Details

Date Published: 11 July 2001
PDF: 10 pages
Proc. SPIE 4333, Smart Structures and Materials 2001: Active Materials: Behavior and Mechanics, (11 July 2001); doi: 10.1117/12.432766
Show Author Affiliations
Akira Kojima, Univ. of Shiga Prefecture (Japan)
Yukio Yoshimura, Ritsumeikan Univ. (Japan)
Hiroshi Iwasaki, Ritsumeikan Univ. (Japan)

Published in SPIE Proceedings Vol. 4333:
Smart Structures and Materials 2001: Active Materials: Behavior and Mechanics
Christopher S. Lynch, Editor(s)

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