| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Lamellar ferroelectric domain structures formed in KH_2PO_4 (KDP) have fractal aspects as well as the periodicity along the normal to the 180ﾟdomain walls. Each half-period of the domain structures is characterized by an n-th pre-fractal of the pentad Cantor set having the fractal dimension D=0.756・・・. We call these structures "the pre-fractal domain structures (PFDS) ". On the basis of the internal energy consisting of both the electrostatic energy U_E relevant to a depolarization field E_d and the domain wall energy U_w relevant to a surface energy density sigma on each wall, I got to have the following expectations. (1) The equilibrium period 2L of PFDS should be proportional to the square root of the thickness d of a plate. (2) Five PFDS having the generations n=0-3 and 3' (a derivative of the 3rd PFDS) should be thermodynamically stabler than any other domain structures characterized by an m-adic Cantor set (m*5). To clarify these expectations I carried out the optical observation and the scanning electron microscopic observation of PFDS on KDP (T_c=123K) , RbH_2PO_4 (RDP,T_c=148K) , KD_2PO_4 (DKDP,T_c=220K) , CsH_2PO_4 (CDP,T_c=156K) and triglycine sulfate (TGS,T_c=322K). The results obtained in the present research are summarized as follows. (1) Five generations of PFDS having n=0-3 and 3'were observed in KDP.(2) PFDS formed in KDP demostrated the relation 2L*d^<1/2>. (3) PFDS were also formed in RDP and DKDP.(4) PFDS were also formed in CDP and TGS.The results (1) and (2) prove that both U_E and U_W play important roles in the formation of PFDS.(3) clarifies that PFDS are formed in the presence of E_d irrespective of the amount of sigma. This is because sigma is proportional to the square root of T_c. (4) clarifies that PFDS are formed in the presence of E_d when sigma has anisotropy, no matter how low the anisotropy is.
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