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

Journal Article · Mon Jan 13 00:00:00 EST 1992 · Physical Review Letters; (United States)

DOI:https://doi.org/10.1103/PhysRevLett.68.232· OSTI ID:5044065

Toulouse, J; DiAntonio, P; Vugmeister, B E; Wang, X M; Knauss, L A ^[1]

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1. Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

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.

• DOE Contract Number: FG02-86ER45258
• OSTI ID: 5044065
• Journal Information: Physical Review Letters; (United States), Vol. 68:2; ISSN 0031-9007
• Country of Publication: United States
• Language: English

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36 MATERIALS SCIENCE
LITHIUM COMPOUNDS
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TANTALUM COMPOUNDS
DIELECTRIC PROPERTIES
FERROELECTRIC MATERIALS
MICROSTRUCTURE
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POLARIZATION
QUATERNARY COMPOUNDS
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CRYSTAL STRUCTURE
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