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Study on the soft mode around the phase transition tenperature of ferroelectric crystals through low-frequency dielectric spectrum measurements.

Research Project

Project/Area Number 06640458
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 固体物性Ⅰ(光物性・半導体・誘電体)
Research InstitutionShizuoka Institute of Science and Technology

Principal Investigator

DEGUCHI Kiyoshi  Shizuoka Institute of Science and Technology, Department of Science and Engineering, Professor, 理工学部, 教授 (10033911)

Project Period (FY) 1994 – 1995
Project Status Completed (Fiscal Year 1995)
Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1995: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1994: ¥1,700,000 (Direct Cost: ¥1,700,000)
Keywordsferroelectrics / phase tansition / soft mode / critical relaxational mode / 誘電分散
Research Abstract

The measurement system of low-frequency dielectric spectrum has been developed. This measurement system is able to speedly provide reliable measurement data in the frequency region of 45 MHz to 15 GHz, and in the temperature region of 80 K to 450 K.
The dielectric spectra of ferroelectric crystals, LHP,LHA,TSCC and D-LTT have been investigated by using the developed measurement system. The results are summarized as follows ;
1.Apparent dielectric critical slowing-down are found around the phase transition temperatures of LHP and LHA.The results indicate that the mechanism of the ferroelectric phase transition is of an order-disorder.
2.TSCC is known to be the first example which shows both the critical softening of phonon mode and the critical slowing-down of the ralaxational mode. The present study clarifies that the critical relaxational mode reported previously is not the relaxational mode but the over-damped soft mode.
3.Critical relaxational mode is not observed in deuterated LTT (D-LTT), as in not-deuteraterd LTT.The nature of the phase transition is not affected by deuteration. However, It is found that the displacive ferroelectric LTT shows unusual deuteration effect of phase transition ; the transition temperature is lowered with increasing the ratio of deuteron. The ferroelectric phase transition disappears in the crystal with the deuteration ratio more than 95%.

Report

(3 results)
  • 1995 Annual Research Report   Final Research Report Summary
  • 1994 Annual Research Report
  • Research Products

    (13 results)

All Other

All Publications (13 results)

  • [Publications] K.Deguchi: "Comparative Studies on the Dielectric Properties of Hydrogen-Borded Ferroelectric PbHAsO_4 and PbHPO_4" to be published.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y.Kobayashi: "X-ray Diffraction and Dielectric Constant Measurement of KH_2PO_4 under High Pressure" Proc.Joint XV AIRAPT & XXXIII EHPRG Int.Conf.Warsaw. 242-244 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y.Iwata: "Neutron Diffraction Study on CDP-DCDP Mixed Crystals" Ferroelectrics. 170. 1-9 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] E.Nakamura: "Two Component Polarization Model in DSP Family" Ferroelectrics. 159. 167-172 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y.Iwata: "A Neutron Diffraction Study on the Deuteration Effect in CsH_2PO_4" J.Phys.Soc.Jpm.63. 4044-4050 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] K.Deguchi: "Comparative Studies on the Dielectric Properties of Hydrogen-Bonded Ferroelectric PbHAsO_4 and PbHPO_4" (to be published).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y.Kobayashi, S.Endo, K.Koto and K.Deguchi: "X-ray Diffraction and Dielectric Constant Measurement of KH_2PO_4 under High Pressure" Proc.Joint XV AIRAPT & XXXIII EHPRG Int.Conf.Warsaw. (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y.Iwata, S.Mitani, I.Shibuya, K.Deguchi and E.Nakamura: "Neutron Diffraction Study on CDP-DCDP Mixed Crystals" Ferroelectrics. Vol.170. 1 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] E.Nakamura and K.Deguchi: "Two Component Polarization Model in DSP Family" Ferroelectrics. Vol.159. 167 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y.Iwata, K.Deguchi, S.Mitani, I.shibuya, Y.Onodera and E.Nakamura: "A Neutron Diffraction Study on the Deuteration Effect in CsH_2PO_4" J.Phys.Soc.Jpn.Vol.63. 4044 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y. Iwata: "Neutron Diffraction Study on CDP-DCDP Mixed Crystals." Ferroelectrics. 170. 1-9 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] E. Nakamura: "Two Component Polarization Model in DSP Family." Ferroelectrics. 159. 167-172 (1994)

    • Related Report
      1995 Annual Research Report
  • [Publications] 岩田豊: "A Neutron Diffraction Study on the Deuteration Effect in CeH2PO_4 crystal." Journal of Physical Society of Japan. 63. 4044-4050 (1994)

    • Related Report
      1994 Annual Research Report

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Published: 1994-04-01   Modified: 2020-05-15  

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