Precursor effects and ferroelectric macroregions in KTa sub 1 minus x Nb sub x O sub 3 and K sub 1 minus y Li sub y TaO sub 3

In the present paper, dielectric, polarization, and Raman results have been combined to identify the existence of a ferroelectric phase transition in the substitutionally disordered dipolar system, KTa{sub 1{minus}{ital x}}Nb{sub {ital x}}O{sub 3}, for low Nb concentrations ({ital x}=1.2%). A detail...

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Bibliographic Details
Published in:Physical review letters 1992-01, Vol.68:2
Main Authors: Toulouse, J., DiAntonio, P., Vugmeister, B.E., Wang, X.M., Knauss, L.A.
Format: Article
Language:English
Subjects:
360202 - Ceramics, Cermets, & Refractories- Structure & Phase Studies
360204 - Ceramics, Cermets, & Refractories- Physical Properties
ALKALI METAL COMPOUNDS
AMINES
AMMONIUM COMPOUNDS
CHALCOGENIDES
CRYSTAL STRUCTURE
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
FERROELECTRIC MATERIALS
LITHIUM COMPOUNDS
MATERIALS SCIENCE
MICROSTRUCTURE
NIOBIUM COMPOUNDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
POLARIZATION
POTASSIUM COMPOUNDS
QUATERNARY COMPOUNDS
RAMAN SPECTRA
REFRACTORY METAL COMPOUNDS
SPECTRA
TANTALUM COMPOUNDS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
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Summary:In the present paper, dielectric, polarization, and Raman results have been combined to identify the existence of a ferroelectric phase transition in the substitutionally disordered dipolar system, KTa{sub 1{minus}{ital x}}Nb{sub {ital x}}O{sub 3}, for low Nb concentrations ({ital x}=1.2%). A detailed study of the first-order TO{sub 2} and TO{sub 3} Raman lines reveals (1) the existence of polar microregions well above {ital T}{sub {ital c}} and (2) the structural transition at {ital T}{sub {ital c}} with the appearance of ferroelectric macroregions. Similar results are obtained in K{sub 1{minus}{ital y}}Li{sub {ital y}}TaO{sub 3} with a quantitative difference due to the slow reorientation of Li. These results can be explained by a random-field model which predicts the coexistence of both dipolar glass and ferroelectric behavior.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.68.232