| Autor: |
Su, C.-C., Vugmeister, B., Khachaturyan, A. G. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 12/15/2001, Vol. 90 Issue 12, p6345, 12p, 5 Graphs |
| Abstrakt: |
A Ginzburg-Landau type theory of interaction of randomly distributed local dipoles in a paraelectric crystal is developed. The interaction is caused by the polarization of the host lattice generated by these dipoles. The obtained effective Hamiltonian of the dipole-dipole interaction is employed for the Monte Carlo simulation of ferroelectric properties of a system with off-center dopant ions producing local dipoles. The computer simulation shows that at low dopant ion concentration the paraelectric state transforms into a macroscopically paraelectric state consisting of randomly oriented polar clusters. These clusters amplify the effective dipole moment and dramatically increase the dielectric constant. The interaction between the clusters results in a spectrum of relaxation time and transition to the relaxor state. The real and imaginary parts of the susceptibility of this state are calculated. At intermediate dopant concentration, the material undergoes a diffuse phase transition into a ferroelectric state smeared within a temperature range. A further increase in the dopant concentration makes the transition sharper and closer to the conventional ferroelectric transition. The results obtained are compared with the behavior of the K[sub 1 -x]Li[sub x]TaO[sub 3] relaxor ferroelectric. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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