| Home | Log-in | Admin | Sitemap |
Home | Program | Detailed Program
Detailed Program
Paper Number : LP-I11
Time Frame : 15:25~15:50
Presentation Date : Friday, 28, November
Session Name : Leadfree Piezoelectrics
Session Chair 1# : Ke Wang
Session Chair 2# : Rintaro Aoyagi
Electromechanical Properties of 0.94Bi0.5(Na0.75K0.25)0.5TiO3-0.06BiAlO3 / Bi0.5(Na0.8K0.2)0.5TiO3 ceramic composite
Soon-Jong Jeong
Korea Electrotechnology Research Institute
Keywords: Lead-free Piezoelectrics, Composites, Process, Property, Structure, Ceramics

We investigated the temperature-dependent polarization and strain of two Bismuth-based perovskite composites. Matrix material was chosen as 0.94Bi0.5(Na0.75K0.25)0.5TiO3-0.06BiAlO3 (BNKT-BA) which have a transition from relaxor to ferroelectric phase (TR-F). Seed materials were Bi0.5(Na0.8K0.2)0.5TiO3 (BNKT) and 0.985Bi0.5(Na0.8K0.2)0.5TiO3 – 0.015BiAlO3 (BNKTBA), which possessing different polarization characteristics. Depending on the test temperature, the different polarization and strain behaviors were observed between the BNKT-BA/BNKT and BNKT-BA/BNKT BA composites. At T=25 oC, the two composites (BNKT-BA/BNKT and BNKT-BA/BNKTBA) exhibited double-like polarization loops and parabolic strain curves which involve an ergodic relaxor-to-normal ferroelectric phase transition with external electric field and a reverse ferroelectric-to relaxor phase transition with removal of the field. At T= 120 oC, two composites have slim polarization and strain curves, which are almost the same as those of the pure BNKT-BA. The high field-induced polarization and strain with respect to temperature for the composites are related to the thermal stability of the ferroelectric seeds, and the nucleation and growth of ferroelectric domain in the relaxor matrix.
Acknowledgements :