1994 Fiscal Year Final Research Report Summary
Effect of Deuteration Observed in Dielectric Dispersion for Hydrogen Bonded Ferroelectrics
| Project/Area Number |
05640390
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Kanazawa Institute of Technology |
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Principal Investigator |
HORIOKA Masakiyo Kanazawa Technical College Kanazawa Institute of Technology Professor, 教授 (60064440)
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| Co-Investigator(Kenkyū-buntansha) |
DEGUTI Kiyoshi Shizuoka Institute of Science and Technology Professor, 教授 (10033911)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Hydrogen-Bonded Ferroelectrics / KH_2PO_4 / KD_2PO_4 / Dielectric Dispersion / Ferroelectric Phase transition / Order-Disorder Type / Proton Tunneling |
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| Research Abstract |
In order to clarify the mechanism of the ferroelectric phase transition in typical hydrogen-bonded ferroelectric crystal, KH_2PO_4(KDP), complex dielectric constants for KDP and KD_2PO_4(DKDP) have been measured in the frequency range from 35MHz to 27GHz. Main results obtained from the analysis of the present data are as follows.
(1) For KDP only one Debye type dipersion which shows a critical slowing-down of dielectric response has been observed, its relaxation frequency being 24GHz.
(2) For DKDP the same type dispersion has been observed, though its relaxation frequency is fairly low and 2.9GHz.
(3) The analysis of the data due to the time-dependent statistics of Ising dipole system on the basis of molecular field approximation and the assumption of Eyring's reaction process gives the results that the characteristics relaxation frequencies of KDP and DKDP are 10^<-13> sec and 10^<-12> sec, respectively. This indicates that the potential barrier in the double minimum potential for KDP should be very small in comparison with kT and nearly zero and the value for DKDP is 1.26kT_c.
(4) From the above mentioned facts it is concluded that the DKDP is of the order-disorder type. For KDP other medels such as tunneling model should be considered.
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