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Detailed Program
Paper Number : LP-P11
Time Frame : 12:00~13:30
Presentation Date : Friday, 28, November
Session Name : Leadfree Piezoelectrics
Session Chair 1# : -
Session Chair 2# : -
Effect of quenching temperature on the ferroelectric and piezoelectric properties of BiFeO3-BaTiO3 bulk ceramics
Mr. Myang Hwan Lee
Changwon National University
Recently, (1-x)BiFeO3-xBaTiO3 (BF-BT) lead-free piezoelectric systems have potential to be applied at a high operation temperature due to their high Tc and high depolarization temperature (Td). BF (rhombohedral phase) and BT (tetragonal phase) solid solutions were observed in the complete compositional range with rhombohedral (x=0.00-0.33), pseudo-cubic (x=0.33-0.92), and tetragonal (x=0.92-1.00) perovskite crystal structures. Leontsev and Eite reported Mn-modified BF-BT ceramics exhibit a small-field piezoelectric constant d33 of 116 pC/N with high Tc of 619 oC at 0.75BF-0.25BT. However, this report cannot be clearly stated in the electrical properties of pure (unmodified) BF-BT system due to high dc conductivity. In this work, the effects of heat-treatment process were investigated in 0.67BF-0.33BT lead-free piezoelectric ceramics. The structure, ferroelectric, and piezoelectric properties of ceramics made by thermal quenching process were investigated and compared to those of furnace cooled ceramics. The lattice constants (a) and lattice distortions (rhombohedral 90o- increased and the fraction of Fe2+ to Fe3+ was reduced in water-quenched ceramics. Ferroelectric and piezoelectric properties were improved with increasing quenching temperature. Small and large-field piezoelectric constants d33 and d33* were 240 pC/N and 283 pm/V in ceramics water quenched at the highest temperature 980 oC.
Acknowledgements : This work was supported by the National Resarch Foundation of Korea [KRF] grant funded by the Korea government [MSIP] (2012-0009457) and by the Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the MEST (2013R1A1A4A01010612, 2012-045424)