C.C. Jin,X.C. Liu,C.H. Liu,Y. Wang,H.L. Hwang,Q. Wang
With excellent piezoelectric properties , (Ba 0.85 Ca 0.15 )(Ti 0.9 Zr 0.1 )O 3 (BCTZ) has been widely used in actuators, capacitors, sensors, etc. In this work, we fabricated BCTZ nanowires (NWs) by using sol-gel based electrospinning technique . By applying plate-electrode and parallel-electrode collectors, random BCTZ NWs (R-NWs) and well-aligned BCTZ NWs (A-NWs) were obtained. X-ray diffraction and high resolution transmission electron microscopy indicated that the NWs have good crystallinity . Furthermore, two flexible energy harvesting devices (EHDs) based on A-NWs and R-NWs were fabricated and their piezoelectric properties were measured. Under a load resistance of 1 MΩ, the output power of the R-NWs-based EHD is only ~0.95 μW while that for A-NWs-based EHD can reach up to ~2 μW, which can easily light a commercial light-emitting diode. Finally, we further demonstrated that the EHD could function as a non-invasive self-powered bio-compatible flexion sensor to apperceive the human knuckle flexion/extension movements.
Yufan Ping,Weimin Xia,Jiahong Zhou,Xiaofang Zhang,Zhong Li
A lead-free tetragonal-phase (Ba 0.94 Ca 0.06 )(Ti 0.95 Zr 0.05 )O 3 (BCTZ) micro sheet is prepared by molten-salt growth method, which exhibits a polarizing behavior of relaxor ferroelectricity and possesses a high dielectric constant ( ε r ) of ~2400. Subsequently, the BCTZ sheet is evenly doped into ferroelectric copolymer P(VDF-TrFE)55/45 mol% with different mass fractions, and the flexible BCTZ/P(VDF-TrFE) composite films are prepared using a conventional solution casting process. ε r of BCTZ/P(VDF-TrFE) increases with the mass content of BCTZ, and reaches 23.8 in 20 wt% BCTZ sample. Meanwhile, at a high electrical field of 30 MV/m, the strain and electric field of BCTZ/P(VDF-TrFE) are in the opposite direction, indicating a negative value of piezoelectric strain coefficient ( d 33 ) caused by inverse piezoelectric effect. In addition, d 33 of different BCTZ/P(VDF-TrFE) films are fitted using a strain-electrical field curve, which firstly increases and then decreases with increases in BCTZ content. As such, a high d 33 of −47.3 pC/N is obtained in BCTZ/P(VDF-TrFE)15/85 wt% film. Thus, this research concerning the inverse piezoelectric effect may provide a reference for designing a piezoelectric composite using in transducers and actuators.
C.C. Jin,X.C. Liu,H.H. Fan,Y. Wang,H.L. Hwang,Y.F. Zhang,Q. Wang
There is great research significance of kinetic energy harvesting as kinetic energy exists in every object's motion. Nanogenerator (NG) is one kind of such devices that can harvest kinetic energy in micro scale . In this work, (Ba 0.85 Ca 0.15 )(Ti 0.9 Zr 0.1 )O 3 nanowires (BCTZ NWs) are successfully prepared by using electrospinning method . Pure perovskite structure of BCTZ NWs is identified by XRD . A high-performance NG is fabricated by mixing with a polydimethylsiloxane polymer and commercial multi-walled carbon nanotubes (MWCNTs). Excellent electric output properties with open-circuit voltage (Voc) of 0.8 V and short-circuit current (Isc) of 8 nA are obtained by human finger tapping . The Isc is two times as large as that of the NG without MWCNTs. The excellent properties indicate that BCTZ-MWCNTs composite has huge potential in energy harvesting.
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