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Effect of Ta Content on Phase Structure and Electrical Properties of Piezoelectric Lead‐Free [(Na 0.535 K 0.480 ) 0.942 Li 0.058 ](Nb 1− x Ta x )O 3 Ceramics
Author(s) -
Zhao Pei,
Tu Rong,
Goto Takashi,
Zhang BoPing,
Yang Shu
Publication year - 2008
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2008.02629.x
Subject(s) - phase boundary , analytical chemistry (journal) , tetragonal crystal system , materials science , orthorhombic crystal system , curie temperature , dielectric , electromechanical coupling coefficient , lattice constant , mineralogy , phase (matter) , crystal structure , chemistry , ceramic , crystallography , diffraction , condensed matter physics , metallurgy , ferromagnetism , physics , optoelectronics , organic chemistry , chromatography , optics
The Li/Ta‐codoped lead‐free (Na,K)NbO 3 ceramics with Na:K ratio of 0.535:0.480 were prepared by normal sintering, whose nominal formula was noted as [(Na 0.535 K 0.480 ) 0.942 Li 0.058 ](Nb 1− x Ta x )O 3 ( x =2, 4, 6, 8, 10, 12, 14, and 16 at.%). The X‐ray diffraction patterns and the corresponding calculation of lattice parameters showed that a morphotropic phase boundary crossing orthorhombic and tetragonal symmetries occurs at the compositions containing 6∼8 at.% Ta. Because of such transitional behavior achieved by optimizing Ta content, the piezoelectric coefficient ( d 33 ), electromechanical coupling coefficient ( k p ), and dielectric constant (ɛ) were enhanced to peak values, 232 pC/N, 39.4%, and 710, respectively. However, the Curie temperature ( T C ) and remanent polarization ( P r ) show a decreasing tendency with raising Ta content, and their maximum values are 462°C and 8.73 μC/cm 2 , respectively.