Ferroelectric polymers, such as poly(vinylidene fluoride-trifluoroethylene)[P(VDF-TrFE) or PVTF] have attracted growing interest in developing flexible devices because of their excellent ferroelectricity and piezoelectricity. High coercive field(Ec) inherent to PVTF for switching its polarization, however, is not beneficial for practical memory or sensor device application. Different strategies, including irradiation and interface control, have been thus developed to reduce Ec. Despite many efforts, a facile approach to tailoring intrinsic Ec of PVTF has not been documented. In this work, an optically controlled Ec was reported, which is achieved for the first time by introducing photosensitive MAPbI3 nanocrystals into PVTF matrix. When exposed to the irradiation of 532 nm laser light, a decreased Ec of the composites can be achieved reversibly by increasing the light density. The decreased level of Ec increases as the MAPbI3 content enhanced, and a 10.7% reduction of Ec can be achieved in 15%(mass fraction) MAPbI3/PVTF samples. These results could be attributed to loading an internal stress on PVTF, which was generated by the photostriction of MAPbI3 nanocrystals. This explanation was further supported by in-situ XRD results under irradiation of 532 nm laser light. Our findings may offer the opportunity to optically modulate the ferroelectric properties of PVTF composites for optimized device performances. 相似文献
The formation of a PZT film of 10–20 m in thickness via an interfacial polymerization of metal-organic precursors has been studied. A commercially available PZT precursor solution developed for dip- or spin-coating was diluted with hexane containing acetylacetone as chelating agent. The solution was poured on water contained in a teflon reaction container of 88 mm inside diameter. A translucent gel film was formed at the interface of the two immiscible liquids. While floating on water it shrank as the evaporation of solvent proceeded until its diameter decreased to about 45% of its initial value. The dried gel film was almost pore free and its thickness was estimated to be about 10 m. 相似文献
Ferroelectric polymers are particularly attractive for applications in flexible electronic devices, and controlling its crystalline phase growth is crucial for obtaining optimized ferroelectric properties. Herein we report that a very low introduction (0.2% (w)) of single-domain ferroelectric PbTiO3 nanoplates can effectively mediate the nucleation and subsequent growth of a crystalline phase within P (VDF-TrFE) (denoted by PVTF), forming highly oriented films and significantly improving the ferroelectric properties due to an alignment of the polarization directions of the polymer and the nanoplates. 相似文献
In this paper a synthetic Poly(L-lactic-co-ϵ-caprolactone) [P(LLA-CL)] (75:25) copolymer has been fabricated into a nanofibrous structure by electrospinning. The polymer crystal structure has been investigated by DSC and x-ray diffraction method. During electrospinning at room temperature, a crystallization of LLA sequence in the P(LLA-CL) copolymer could not form, while a relatively regular arrangement of CL sequence was observed. In order to obtain a tubular scaffold, a rotating mandrel was designed to collect the fiber, so that the tubular scaffold can be retrieved from the mandrel with an inner diameter same as that of the outer diameter of the mandrel. An auxiliary electrode with a sharp edge and a negative charge was set under the mandrel to guide the fiber deposition on the mandrel. When the sharp edge bar was vertical to the rotating axle of the mandrel and just beneath the spinning nozzle, nanofibers with circumferential alignment were obtained. With this method it is possible to obtain a tubular scaffold with suitable fiber alignment for blood vessel tissue engineering. 相似文献
Summary: We have used the process of electrospinning to produce fibers of poly(dicyclopentadiene) with diameters on the submicron scale. The material, formed from a monomer‐catalyst solution, polymerized in flight during the electrospinning process. Fibers were collected over trenches etched in silicon and the Young's moduli were measured using an atomic force microscope to measure force‐displacement curves. The resulting values of Young's moduli are larger than typical values for bulk polymer material.
PZT (PbZr0.53Ti0.47O3) films and powders have been prepared by a precursor mixture containing Pb(NO3)1.5EO3 (EO3=triethylene glycol) and Zr- and Ti-methoxy ethanolates. The gel films have been deposited on Si/Ti/Pt substrates and on glass substrates from which they can easily be removed. The PZT films on the Si/Ti/Pt substrates were prepared with thicknesses up to 200 nm per layer after heating to 700°C. The phase development on heat-treatment of loose gel films to yield PZT was investigated by Powder-XRD, FT-IR, SEM-EDS, TEM-EDS, thermo-mass spectroscopy and DSC and the PZT was found to form in the region 550–700°C. PZT powders of 50–5000 nm sizes were prepared by hydrolysis under basic conditions and washing with water followed by heat-treatment to 650°C. 相似文献
We present a hydrothermal method to deposit PZT films. It uses a single-step hydrothermal process and user-friendly precursors. Pb(Zr0.52,Ti0.48)O3 polycrystalline films, 5–10 μm thick, were produced in an aqueous basic solution (4M KOH) on a titanium substrate in a closed autoclave at 180 °C. A time-depending study to see the evolution of the films' formation is described. Some actuation testing is also presented. 相似文献
