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Full-Text Articles in Physics
Regulating Self-Organizing Nanostructures Via External Mechanism, Jiangyu Li, Q. G. Du, Stephen Ducharme
Regulating Self-Organizing Nanostructures Via External Mechanism, Jiangyu Li, Q. G. Du, Stephen Ducharme
Stephen Ducharme Publications
Self-organizing nanostructures are ubiquitous in both natural and synthetic materials. They are not only appealing scientifically, by revealing the intrinsic atomic and molecular interactions that might be difficult to detect otherwise, but may also hold the key for the development of novel functional structures and devices. For their technological potential to be fully realized, the size, morphology, and distribution of the self-organizing nanostructures must be regulated. In this paper, we investigate the principles under which the self-organizing nanostructures can be regulated via external mechanisms. Using nanomesa and nanowell formation in polyvinylidene fluoride trifluoroethylene copolymer film as an example, we demonstrate …
Why Are Ferroelectric Polymers Difficult To Find – And Difficult To Verify, Stephen Ducharme
Why Are Ferroelectric Polymers Difficult To Find – And Difficult To Verify, Stephen Ducharme
Stephen Ducharme Publications
The field of electrets encompasses a wide range of materials that maintain an external electric field due to alignment of internal electric dipoles or trapped charge, or both [1]. Polymers incorporating molecular dipoles constitute an important class of electrets, and so it is fitting that we consider the conditions under which such a polymer can also be considered a ferroelectric [2]. Further, because ferroelectric polymers have many uses, it is fruitful to consider how their properties depend on molecular structure [3].
Local Probing Of Relaxation Time Distributions In Ferroelectric Polymer Nanomesas: Time-Resolved Piezoresponse Force Spectroscopy And Spectroscopic Imaging, Brian J. Rodriguez, Stephen Jesse, Jihee Kim, Stephen Ducharme, Sergei V. Kalinin
Local Probing Of Relaxation Time Distributions In Ferroelectric Polymer Nanomesas: Time-Resolved Piezoresponse Force Spectroscopy And Spectroscopic Imaging, Brian J. Rodriguez, Stephen Jesse, Jihee Kim, Stephen Ducharme, Sergei V. Kalinin
Stephen Ducharme Publications
Time-resolved piezoresponse force spectroscopy (TR-PFS) and spectroscopic imaging are developed to probe the spatial variability of relaxation behavior in nanoscale ferroelectric materials and structures. TR-PFS was applied to study polarization dynamics in polyvinylidine fluoride and trifluoroethylene nanomesas. We demonstrate that polarization relaxation in ferroelectric polymers is slow even on the ~10 nm length scale of piezoresponse force microscopy (PFM) signal generation. Furthermore, the relaxation times are found to be nonuniform within the nanomesa, indicative of a complex internal structure. The applicability of TR-PFM for studies of polarization dynamics in ferroelectric polymers and relaxors is discussed.
Polarization Switching Kinetics At The Nanoscale In Ferroelectric Copolymer Langmuir-Blodgett Films, R. V. Gaynutdinov, O. A. Lysova, A. L. Tolstikhina, S. G. Yudin, V. M. Fridkin, Stephen Ducharme
Polarization Switching Kinetics At The Nanoscale In Ferroelectric Copolymer Langmuir-Blodgett Films, R. V. Gaynutdinov, O. A. Lysova, A. L. Tolstikhina, S. G. Yudin, V. M. Fridkin, Stephen Ducharme
Stephen Ducharme Publications
The polarization switching kinetics of ferroelectric Langmuir–Blodgett films of vinylidene fluoride-trifluoroethylene copolymer were investigated by piezoresponse force microscopy with a resolution of 100 nm. The switching time in response to a localized voltage pulse exhibits an exponential dependence on reciprocal voltage, which is consistent with nucleation-limited switching dynamics.
Effects Of An External Electric Field On The Ferroelectric-Paraelectric Phase Transition In Polyvinylidene Fluoride-Trifluoroethylene Copolymer Langmuir-Blodgett Films, Matt Poulsen, A. V. Sorokin, Shireen Adenwalla, Stephen Ducharme, V. M. Fridkin
Effects Of An External Electric Field On The Ferroelectric-Paraelectric Phase Transition In Polyvinylidene Fluoride-Trifluoroethylene Copolymer Langmuir-Blodgett Films, Matt Poulsen, A. V. Sorokin, Shireen Adenwalla, Stephen Ducharme, V. M. Fridkin
Stephen Ducharme Publications
X-ray diffraction and capacitance measurements have been employed to study the structural and dielectric behavior of the ferroelectric-paraelectric phase transition under the influence of a large external electric field. The samples under study are ultrathin (15–100 nm) Langmuir–Blodgett films of a copolymer of vinylidene fluoride (70%) with trifluoroethylene (30%) deposited on aluminum-coated silicon. In situ θ-2θ x-ray diffraction was used to measure the change in interlayer spacing perpendicular to the film surface, corresponding to the (110) direction and indicating that the polymer chains along (001) lie predominantly in the plane, while capacitance measurements were used to monitor the …
Switching Kinetics Of Ferroelectric Polymer Nanomesas, Christina M. Othon, Jihee Kim, Stephen Ducharme, V. M. Fridkin
Switching Kinetics Of Ferroelectric Polymer Nanomesas, Christina M. Othon, Jihee Kim, Stephen Ducharme, V. M. Fridkin
Stephen Ducharme Publications
The switching dynamics and switching time of ferroelectric nanomesas grown from the paraelectric phase of ultrathin Langmuir–Blodgett vinylidene fluoride and trifluoroethylene copolymer films are investigated. Ferroelectric nanomesas are created through heat treatment and self-organization and have an average height of 10 nm and an average diameter of 100 nm. Ferroelectric nanomesas are highly crystalline and are in the ferroelectric phase and switch faster than 50 μs. The dependence of switching time on applied voltage implies an extrinsic switching nature.
Oligo(Vinylidene Fluoride) Langmuir-Blodgett Films Studied By Spectroscopic, Rafal Korlacki, J. Travis Johnston, Jihee Kim, Stephen Ducharme, Daniel W. Thompson, Vladimir M. Fridkin, Zhongxin Ge, James M. Takacs
Oligo(Vinylidene Fluoride) Langmuir-Blodgett Films Studied By Spectroscopic, Rafal Korlacki, J. Travis Johnston, Jihee Kim, Stephen Ducharme, Daniel W. Thompson, Vladimir M. Fridkin, Zhongxin Ge, James M. Takacs
Stephen Ducharme Publications
Thin films of amphiphilic vinylidene fluoride oligomers prepared by Langmuir–Blodgett deposition on silicone substrates were investigated by comparing experimental and theoretical mid-infrared (IR) spectra. The experimental spectra were obtained using infrared spectroscopic ellipsometry. Theoretical spectra were calculated using density functional theory. Excellent correspondence of major IR bands in both data sets shows that the molecular backbone is oriented with the long axis normal to the substrate plane. This is in contrast to poly vinylidene fluoride[1] LB films, in which the polymer chains are parallel to the substrate.