No abstract available

No abstract available

No abstract available

[en] Generalizing the known data for ferroelectrics of A₂B₂O₇ type (LnTi₂O₇, in particular) geometrical conditions of existence of laminated perovskite-like structure are determined: 0.603 A < anti Rsub(Bsup(6)) <= 0.665 A, anti Rsub(Asup(12))/Rsub(Bsup(6)) > 2.045. The geometrical conditions presented are necessary but not sufficient. A supposition is made that phases GaLnTiNbO₇ (Ln = Pr - Eu) and CaLnTiTaO₇ (Ln = La - Eu) with laminated perovskite-like structure can be prepared under high pressures

[en] The 10th International Conference on ferroelectricity was held on 3 - 7 September, 2001 in Madrid, Spain. At a plenary session of the conference, a talk was delivered, whose content is presented in the present paper. The paper is primarily concerned with the work of V L Ginzburg and other Russian physicists on the theory of ferroelectric phenomena. (conferences and symposia)

[en] We reveal that the role of the higher non-linear local interactions in the conventional theoretical models developed to describe phase transitions in type II incommensurate systems is underestimated. Their consistent consideration in the thermodynamic potential expansion allows one to remove key contradictions in explanation of the experimental data for ferroelectric Sn₂P₂Se₆ in the vicinity of the modulated-commensurate phase transition point

[en] We examine the validity of nonlinear thermodynamic models which incorporate the contribution of electrostatic coupling and interfacial space charge in ferroelectric-paraelectric bilayers. Inconsistency of the directions between build-in polarization and field is found. Evolution of ferroelectricity does not follow the variation in coupling strength between different layers. In addition, we observe that the field-induced polarization in the paraelectric layer deviates from the polarization derived by thermodynamic theory. These findings indicate that the current versions of thermodynamic models need to be modified. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

[en] Short note

[en] In this paper, the effective pyroelectric coefficient and polarization offset of the compositionally step-like graded multilayer ferroelectric structures have been studied by use of the first-principles approach. It is exhibited that the dielectric gradient has a nontrivial influence on the effective pyroelectric coefficient, but has a little influence on the polarization offset; and the polarization gradient plays an important role in the abnormal hysteresis loop phenomenon of the compositionally step-like graded ferroelectric structures. Moreover, the origin of the polarization offset is explored, which can be attributed to the polarization gradient in the compositionally step-like graded structure.

[en] The authors propose electrets as a radiotransparent transducer for dosimetry in radiodiagnosis and describe a compact unit for the fabrication of electrets and the carrying-out of dose measurements. (orig.)