Effects of SrTiO3 on dielectric and piezoelectric properties of K0.48Na0.48Li0.04Nb0.96Ta0.04O3-based piezoceramics

► Sodium potassium niobate based piezoceramics modified with SrTiO3 (ST) were prepared. ► Crystal structure, microstructure and dielectric properties of ceramics were investigated. ► Addition of ST more than 3mol% changed ferroelectric behavior from normal to relaxor. ► Coexistence of two structures...

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Bibliographic Details
Published in:Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2013-03, Vol.178 (4), p.277-281
Main Authors: Bafandeh, Mohammad Reza, Abbasi, Mohammad Hasan, Saidi, Ali, Lee, Jae-Shin
Format: Article
Language:English
Subjects:
Dielectric response
Ferroelectrics
Microstructure
Piezoelectricity
Sintering
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Summary:► Sodium potassium niobate based piezoceramics modified with SrTiO3 (ST) were prepared. ► Crystal structure, microstructure and dielectric properties of ceramics were investigated. ► Addition of ST more than 3mol% changed ferroelectric behavior from normal to relaxor. ► Coexistence of two structures in ceramic with 1mol% ST enhanced piezoelectric constant. In this study, (100−x) K0.48Na0.48Li0.04Nb0.96Ta0.04O3−xSrTiO3 (0≤x≤10) ceramics were fabricated via normal sintering of synthesized powder by using solid state reaction. All ceramics revealed pure perovskite structure, indicating formation of solid solution between KNNLT and ST up to 10%. With increasing x, the crystal structure of ceramics changed from orthorhombic to tetragonal and finally pseudocubic symmetry when x=10. Ceramic containing 1% ST had orthorhombic and tetragonal symmetries, simultaneously. Investigation of the variation of dielectric constant of ceramics versus temperature revealed that for ceramic with x=1, polymorphic phase transition (PPT) temperature between orthorhombic and tetragonal is less than room temperature. Thus coexistence of two different structures in this ceramic is due to vicinity of its composition to morphotropic phase boundary (MPB). As a result, the maximum piezoelectric constant was measured for this ceramic. Ceramics containing 5 and 7.5% ST tend to appear relaxor ferroelectric behavior which is because of chemical inhomogeneities in both A- and B-sites of the ABO3 perovskite structure.
ISSN:0921-5107
1873-4944
DOI:10.1016/j.mseb.2012.11.022