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Ferroelectric Phase Transition (ferroelectric + phase_transition)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Characterization of phase transition in new ferroelectric 2-aminopyridine phosphate crystal

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2003
A. Hek
Abstract The dielectric properties of 2-APP, a new ferroelectric crystal, were investigated around the ferroelectric phase transition at 103.5 K. The temperature dependence of electric permittivity was measured at dc electric fields up to 1000 kV/m. The electric permittivity was also measured in the paraelectric phase at constant temperature as a function of electric field intensity up to 150 kV/m. The results are discussed in the framework of the classical dielectric state equation and expansion coefficients A, B and C were estimated. It is found that the phase transition is of second order. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Low temperature structural transformations of dilute KTa1,xNbxO3: x = 0.018, quantum superparaelectric or reentrant glass scenario?

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005
V. A. Trepakov
Abstract Impurity induced structural transformations are studied for KTa1,xNbxO3 with x = 0.0018 (KTN-1.8) by low-frequency linear and non-linear dielectric spectroscopy techniques. Nb admixture leads to the appearance of a sharp ,,(T) maximum accompanying the ferroelectric phase transition at TC , 27 K, and a glass-like state formation at lower temperatures. The linear permittivity evidences properties inherent to systems being near the quantum-mechanical displacive limit and shows the long range polar order with macroscopic polarization formation at ,27 K. This conclusion was proven by nonlinear polarization response stuidy under dc electric field action, which evidenced also the proximity of the three-critical point. Above 27 K, the nonlinearity increases at cooling in accordance with the Devonshire theory for the paraelectric phase of conventional ferroelectrics. Below 27 K, the random distribution of Nb5+ ions and related system's inhomogeneities provoke a new low temperature phase state formation, which can be treated as reentrant polar-glass. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Electro-optical properties of ZnO-BaTiO3 -ZnO heterostructures grown by pulsed laser deposition

ANNALEN DER PHYSIK, Issue 1-2 2004
M. Schubert
Abstract Electro-optical birefringence measurements by spectroscopic ellipsometry on ZnO-BaTiO3 -ZnO heterostructures, grown by pulsed laser deposition on (0001) sapphire are reported. Wurtzite-structure ZnO layers serve as transparent conducting electrodes. An interesting hysteresis is observed, tentatively assigned due to coupling between wurtzite and ferroelectric polarization, and ferroelectric phase transition. [source]

Dielectric and calorimetric studies of ferroelectric phase transitions in Li(2,x)NaxGe4O9 crystals

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 15 2005
I. Cebula
Abstract The ferroelectric phase transitions of LiNaGe4O9, Li1.1Na0.9Ge4O9, Li1.2Na0.8Ge4O9 and Li1.7Na0.3Ge4O9 crystals were studied. Experiments were carried out by means of classical dielectric measurements and using an AC calorimetric specific-heat measuring system. Critical behaviour is explained within Landau theory. The expansion coefficients of the state equation are determined. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]