Regensburg 1998 – scientific programme

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DF: Dielektrische Festkörper

DF 3: Relaxation und Phasenübergänge

DF 3.2: Talk

Tuesday, March 24, 1998, 10:50–11:10, H11

Phase Transitions in doped Quantum Paraelectrics studied with the Transverse Ising Model — •Y.G. Wang and W. Kleemann — Gerhard-Mercartor-Universit"at - Gesamthochschule Duisburg - D-47048 Duisburg

The phase transition properties of KTL(Li_xK₁−xTaO₃)like quantum paraelectrics are studied within the framework of the transverse Ising model, whereby different kinds of pseudo-spins represent different unit cells. Concentrational phase transitions are found for appropriate parameters. The substional ions act as pinning-centers of the polarization. The dependence of the polarization, Curie temperature and dielectric permittivity on the concentration of the substitutional ions is investigated. The effects of intrinsic random fields and external electric fields on the phase transition behavior are simulated. The theoretical results are compared with the experimental observations and good agreement is obtained.

Supported by the Alexander von Humboldt-Stiftung