| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1997: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
Recently much attention has been given to diffuse phase transition (relaxor behavior) from viewpoint of fundamental interest and also practical importance in the development of ferroelectric materials. In this work, some relaxor-based ferroelectric single crystals with microscopically controlled ordering degree of chemical ordering at B-site in the complex perovskite Pb(B,B')O3 structure were successfully grown, by using PbO-flux method. Structural, optical, dielectric, pyroelectric, piezo-electric properties of single crystals and ceramics of relaxor-based ferroelectrics such as Pb(Mg_<1/3> Nb_<2/3>)O_3(PHN), Pb(Zn_<l/3>Nb_<2/3>)O_3(PZN), Pb(In_<l/2>Nb_<l/2>)O_3(PIN), Pb(Mg_<1/2>W_<1/2>)O_3(PMW), Pb(Sc_<1/2>Ta1_<1/2>)O_3(PST) and their solid solutions with normal ferroelectric PbTiO_3(PT) and PbZrO_3(PZ), and so on have been investigated as functions of compositions, temperature, pressure, and dc-biasing fields by X-ray diffraction, polarized microscopy, Raman scattering and impedance
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gain phase analyser. We found that the volume effects(namely, the excess volume accompanied with the disordering at the B-site) play an important role in the manifestation of the relaxor behavior. Such volume and chemical effects were found to be performed by suitable substitution effects at B-site. Moreover, large ferroelectric properties such as giant spontaneous polarization, permittivity and electromechanical coupling were found to be induced by the coexistence of heterophases (many kinds of domains such as ferroelectric, antiferroelectric and relaxor / mesoscopical coexistence of microclusters/ a number of sites of polarization) near morphotropic phase boundary in relaxor-based ferroelectric solid solutions. From such coexistence in relaxor ferroelectrics, development for gradient functional ferroelectric materials (e.g., multi-functional sensor fusion) can be expected. In this work, especially, superior dielectric, pyroelectric and piezoelectric properties could be found for PIN-PT, PIN-PZ and PMW-PT solid solution systems. Less
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