| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
|
|---|
| Research Abstract |
To investigate the domain structures and the interface structures between different materials and between different phases of a material, we proposed, based on the Landau theory, a one-dimensional model, where two semi-infinite materials contact at the interface, interacting by bi-linear coupling.
Using this model, we obtained the polarization profiles and the interface energies for more realistic cases of ferroelectrics undergoing the first order transition. Followings are found.
(1)In the case of small interaction constant at the interface, two materials are just placed independently, and therefore the gap of the polarization values at the interface is large and the interaction energy at the interface is small.
(2)In the case of large interaction constant at the interface, and the polarization of the softer material is "pulled" towards the one of the harder material, with the gap of the polarizations at the interface decreasing with increasing the interaction parameter.
(3)The interface energy becomes maximum at a certain magnitude of the interaction parameter.
By the present model the extrapolation length, assumed a priori in the thin film model proposed by Tilley and Zeks, turned out not to be a material constant, but rather to be obtained in a natural way, depending upon the combination of two materials concerned.
Since two materials are assumed to be semi-infinite, the effect of the formed interface on the extensive quantities like polarization is not significant, but the one on the intensive quantities like the coercive field can be remarkable. In fact the interface triggered polarization reversals are found to occur with a reduced coercive field.
|
