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research article

Synthesis and dielectric characterization of potassium niobate tantalate ceramics

Venkatesh, J.
•
Sherman, V.
•
Setter, N.  
2005
Journal of the American Ceramic Society

The preparation and dielectric properties of potassium niobate tantalate (KTN) have been investigated with the aim of exploring the material's potential for ferroelectric tunable applications. The samples were prepared both by conventional sintering in air and by uniaxial hot pressing. A relative average density greater than 92% was obtained with both methods. An inhomogeneous Nb/Ta distribution was found in the samples prepared by both methods, but the inhomogeneity extent was lower in the hot-pressed samples. While both sintering processes resulted in ceramics of lower transition temperatures in comparison with the reported results on single crystals, a relative up shift of the temperature (T-max) at which the dielectric constant is maximum was found for hot-pressed samples compared with that of samples sintered in air. All the samples exhibited strong frequency dispersion in dielectric properties. The effect of DC bias at room temperature was measured and modeled using the Landau-Devonshire model. It was found that the nonlinear coefficient beta of KTN, which is important for tunable applications, is comparable with the value reported on KNbO3 and SrTiO3 single crystals. A dielectric tunability of 16% and 42% at room temperature was demonstrated under 20 kV/cm for the sintered and hot-pressed ceramics, respectively. The loss tangent, low at megahertz frequencies, was augmented to 9%-17% at low gigahertz frequencies. This is believed to be related to the frequency dispersion observed in the ceramics because of charged defects.

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Type
research article
DOI
10.1111/j.1551-2916.2005.00606.x
Web of Science ID

WOS:000233624400016

Author(s)
Venkatesh, J.
Sherman, V.
Setter, N.  
Date Issued

2005

Published in
Journal of the American Ceramic Society
Volume

88

Issue

12

Start page

3397

End page

3404

Subjects

single-crystals

•

microwave devices

•

thin-films

•

ferroelectrics

Note

Sherman, V Ecole Polytech Fed Lausanne, Swiss Fed Inst Technol, Ceram Lab, CH-1015 Lausanne, Switzerland Ecole Polytech Fed Lausanne, Swiss Fed Inst Technol, Ceram Lab, CH-1015 Lausanne, Switzerland

988TS

Cited References Count:32

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LC  
Available on Infoscience
August 21, 2006
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/233579
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