| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
The essential assumptions of the Spherical Random Bond Random Field model of relaxor ferroelectrics, proposed by Brine et al., are that (1)the energy due to the dipole interaction is isotropic, (2)the larger the cluster, the larger the polarization and the contribution to the dielectric susceptibility. On the other hands, it was pointed out that in ferroelectric solid solutions with the concentration in the vicinity of the morphotropic phase boundary the free energy is almost isotropic, and it is the physical origin of excellent properties like large dielectric constant, small elastic stiffness constant and large piezoelectric constant. It may be worthwhile to incorporate these ideas into one model, and effort has been made along such lines.
In constructing models of relaxor ferroelectrics it is necessary to assume some kind randomness, like random bonds, random fields and other physical factors. One of the promising assumptions may be that some parameters appearing in the free energy function are randomly distributed in a specimen. Boundaries formed between clusters, each being homogeneous in such parameters, must be considered separately, according to the nature of clusters. The 90 degree ferroelectric domain walls and the interfaces between dielectrics and ferroelectrics are studied upon the models based on the Landau-Ginzburg free energy functionals.
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