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Detailed Program
Paper Number : LP-P12
Time Frame : 12:00~13:30
Presentation Date : Friday, 28, November
Session Name : Leadfree Piezoelectrics
Session Chair 1# :
Session Chair 2# :
Effect of Ta-substitution on the dielectric, ferroelectric and
Rizwan Ahmed MALIK
Changwon National University
The effect of Ta substitution on the crystal structure, electromechanical, dielectric, and piezoelectric properties of BNKTT-ST (0.96Bi0.5(Na0.84K0.16)0.5Ti1-xTaxO3]–0.04SrTiO3 where x = 0.00 – 0.030) ceramics has been investigated. X-ray diffraction patterns revealed that Ta doping resulted in a transition from coexistence of rhombohedral and tetragonal phases to a pseudocubic phase. Both the dielectric constant and depolarization temperature decreased with an increase in Ta-content. The polarization and strain hysteresis loops indicate that the ferroelectric order of the BNKT-ST ceramics was significantly disrupted by the addition of Ta content, leading to degradation in the remnant polarization and coercive field.
However, the destabilization of the ferroelectric order is accompanied by significant enhancements in the bipolar and unipolar strains. A large electric field-induced strain (S = 0.38%) and a corresponding normalized strain (Smax/Emax = 633 pm/V) were observed under 6 kV/mm when 2% Ta was substituted on Ti sites. This significant strain enhancement may be attributed to a reversible field-induced ergodic relaxor to ferroelectric phase transformation.
Acknowledgements : This work is supported by the Basic Research program through the National Research Foundation of Korea (NRF) funded by Ministry, Science and Technology (MEST) (2011-0030058)