Browsing by Author "You, Lu"

Now showing 1 - 2 of 2

Flexible PbZr0.52Ti0.48O3 Capacitors with Giant Piezoelectric Response and Dielectric Tunability
(2017-08-01)
Gao, Wenxiu
;
You, Lu
;
Wang, Yaojin
;
Yuan, Guoliang
;
Chu, Ying-Hao
Oxide ferroelectric ceramics and single crystals for flexible wearable device applications significantly suffer from the nature of hardness and brittleness due to their small maximum elastic strain and technological challenge in thinning to micrometer or nanometer scale. Although many oxide films are thin enough to be flexible, their rigid substrates restrain their piezoelectric d(33) coefficient and limit their flexible performance. Here, the large-scale PbZr0.52Ti0.48O3 (PZT) films with SrRuO3 (SRO) buffered layer are grown on the 10 mu m thick flexible mica substrate. An amplified longitudinal piezoelectric d(33) of about 1200 pm V-1 is achieved in an SRO/PZT/Pt capacitor due to the direct mechanical coupling between PZT and flexible mica via the d(31) piezoelectric tensor. The SRO/PZT/Pt capacitor shows a saturated polarization of approximate to 60 mu C cm(-2) and a dielectric tunability of approximate to 90%. Most importantly, the electric properties do not show obvious deterioration after repeatedly bending 10 000 times at a 2.2 mm radius. The flexible ferroelectric capacitors have potential applications in next-generation wearable devices and micro-electromechanical systems.
Universal Ferroelectric Switching Dynamics of Vinylidene Fluoride-trifluoroethylene Copolymer Films
(2014-04-24)
Hu, Wei Jin
;
Juo, Deng-Ming
;
You, Lu
;
Wang, Junling
;
Chen, Yi-Chun
In this work, switching dynamics of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer films are investigated over unprecedentedly wide ranges of temperature and electric field. Remarkably, domain switching of copolymer films obeys well the classical domain nucleation and growth model although the origin of ferroelectricity in organic ferroelectric materials inherently differs from the inorganic counterparts. A lower coercivity limit of 50 MV/m and 180 degrees domain wall energy of 60 mJ/m(2) are determined for P(VDF-TrFE) films. Furthermore, we discover in copolymer films an anomalous temperature-dependent crossover behavior between two power-law scaling regimes of frequency-dependent coercivity, which is attributed to the transition between flow and creep motions of domain walls. Our observations shed new light on the switching dynamics of semi-crystalline ferroelectric polymers, and such understandings are critical for realizing their reliable applications.