MECHANISM FOR APPEARANCE OF MULTIFUNCTIONAL OF FERROELECTRICS WITH GIANT SPONTANEOUS POLARIZATION AND DEVELOPMENT FOR MULTIFUNCTIONAL SENSOR FUSION

漫射相变（弛豫行为）在铁电材料的发展中具有重要的基础和实际意义，近年来受到了广泛的关注。本文采用PbO-flux法制备了Pb（B,B′）O3复合钙钛矿结构中具有微观可控B位化学有序度的弛豫基铁电单晶。本文研究了弛豫基铁电体Pb(Mg_<1/3> Nb_<2/3>)O_3（PHN）、Pb(Zn_< 1/3> Nb_<2/3>)O_3（PZN）、Pb(In_< 1/2> Nb_< 1/2>)O_3（PIN）、Pb(Mg_<1/2>W_<1/2>)O_3（PMW）、Pb(Sc_<1/2> ta_1 <1/2>)O_3（PST）及其固溶体PbTiO_3（PT）、PbZrO_3（PZ）等单晶和陶瓷的结构、光学、介电、热释电、压电特性。通过x射线衍射、偏振光显微镜、拉曼散射和阻抗等方法对直流偏置场进行分析。我们发现体积效应（即过量的体积伴随着b位点的无序）在松弛行为的表现中起重要作用。这种体积效应和化学效应是通过在b位点上适当的取代效应来实现的。此外，在弛豫型铁电固溶体中，异相（铁电、反铁电和弛豫/微团簇/多个极化位点等多种畴）在亲晶相边界附近共存，可诱发巨大的自发极化、介电常数和机电耦合等铁电性能。从弛豫铁电体中的这种共存，可以预期梯度功能铁电材料（例如多功能传感器融合）的发展。在这项工作中，PIN-PT、PIN-PZ和PMW-PT固溶体体系具有优异的介电、热释电和压电性能。少

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 … More 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