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Phase Transition, Electrical Properties, and Temperature‐Insensitive Large Strain in BiAlO 3 ‐Modified Bi 0.5 (Na 0.75 K 0.25 ) 0.5 TiO 3 Lead‐Free Piezoelectric Ceramics
Author(s) -
Ullah Aman,
Ahn Chang Won,
Hussain Ali,
Lee Sun Young,
Kim Ill Won
Publication year - 2011
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.1551-2916.2011.04595.x
Subject(s) - ferroelectricity , materials science , dielectric , tetragonal crystal system , analytical chemistry (journal) , phase transition , x ray crystallography , coercivity , diffraction , piezoelectricity , permittivity , hysteresis , transition temperature , mineralogy , condensed matter physics , crystallography , crystal structure , chemistry , optics , composite material , physics , optoelectronics , chromatography , superconductivity
Lead‐free piezoelectric (1– x )( Bi 0.5 (Na 0.75 K 0.25 ) 0.5 TiO 3 )‐ x BiAlO 3 ( BNKT25 ‐ x BA, x = 0–0.100) ceramics were synthesized using a conventional solid‐state reaction method. The effect of BA addition into the BNKT25 ceramics was investigated by X‐ray diffraction, dielectric and ferroelectric characterizations, and electric field‐induced strain. X‐ray diffraction revealed a phase transition from a tetragonal to a pseudocubic phase at x = 0.050. As the BA content increased, the maximum dielectric constant as well as the depolarization temperature ( T d ) decreased. The polarization and strain hysteresis loops indicate that the addition of BA significantly disrupts the ferroelectric order of the BNKT25 ceramics leading to a degradation of the remanent polarization and coercive field. However, the destabilization of the ferroelectric order is accompanied by a significant enhancement in the unipolar strain which peaks at x = 0.025 with a value of ~0.29%, which corresponds to a normalized strain, d * 33 (= S max / E max ) of 484 pm/V. It was observed that the unipolar strain of 0.025 x BA is fairly temperature‐insensitive up to 150°C, even at 130°C the d * 33 is as large as ~415 pm/V.