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Detailed Program
Paper Number : LP-O04
Time Frame : 11:47~11:59
Presentation Date : Friday, 28, November
Session Name : Leadfree Piezoelectrics
Session Chair 1# : Wook Jo
Session Chair 2# : Wataru Sakamoto
Piezoelectric properties of Lead-free 0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 epitaxial thin films grown onto Si (001) substrate by Pulsed Laser Deposition for Energy Harvesting Applications
Jae-Ryong LIM
Chungnam National University
Keywords: Piezoelectric thin films, 0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT),
Lead-free, Pulsed laser deposition (PLD),

Energy harvesting from irregular mechanical actions in variable and uncontrollable environments is an effective approach for powering wireless mobile electronics to meet a wide range of applications in our daily life. Piezoelectric thin film is robust and can be stimulated by tiny physical motions over a range of frequencies. PbZrTiO3 (P ZT) is most widely used as piezoelectric ceramic, and it is faced on worldwide criticism due to its lead toxicity, so there is need to find a lead free piezoelectric material which is comparable to PZT. There is report that lead free piezoelectric ceramic system 0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) which shows a surprisingly high piezoelectric coefficient of d33 = 620 pC/N at optimal composition, it is comparable PZT's piezoelectric coefficient (PZT has d33 = 500 - 600 pC/N). So, BZT-BCT is the best candidate of piezoelectric ceramics for energy harvesting applications.
We studied about BZT-BCT thin films grown at high temperature on LSCO/CeO2/YSZ/p-Si(100) substrates using pulsed laser deposition (PLD) and Pt thin films were prepared as top electrode by DC sputtering. La0.5Sr0.5CoO3 (LSCO) thin films is a bottom electrode and it was deposited at various temperature (450~650¡É) and minimum resistivity is 2.2¡¿10-3¥Øcm at 550¡É. CeO2 and Yttria Stabilized Zirconia (YSZ) thin films used as buffer layer for epitaxial growth of BZT-BCT thin films. XRD results reveal (100) preferred orientation of BZT-BCT and LSCO thin films and full width at half maximum (FWHM) of rocking curve is 2.63¡Æ and 2.19¡Æ each. and We can see 4 fold symmetry of all thin films through phi-scan measurement. Also, Polarization Electrical field loop and leakage current of BZT-BCT were measured, Remnant polarization (Pr) is 5.5¥ìC/cm2 and coercive field (Ec) is 15kV/cm

References:
[1] W. Liu and X. Ren, Phys. Rev. Lett. 103, 257602 (2009).
Acknowledgements :