scholarly journals Adaptive Shell Spherical Reflector Actuated with PVDF-TrFE Thin Film Strain Actuators

Actuators ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Kainan Wang ◽  
Thomas Godfroid ◽  
Damien Robert ◽  
André Preumont
Keyword(s):  
Thin Film ◽  
Active Material ◽  
Quadratic Model ◽  
Influence Functions ◽  
Regularization Technique ◽  
Thin Polymer ◽  
Optical Modes ◽  
Electrostrictive Material ◽  
Ill Conditioning ◽  
Good Agreement

This paper discusses the design and manufacturing of a thin polymer spherical adaptive reflector of diameter D=200 mm, controlled by an array of 25 independent electrodes arranged in a keystone configuration actuating a thin film of PVDF-TrFE in d31-mode. The 5 μm layer of electrostrictive material is spray-coated. The results of the present study confirm that the active material can be modelled by a unidirectional quadratic model and that excellent properties can be achieved if the material is properly annealed. The experimental influence functions of the control electrodes are determined by a quasi-static harmonic technique; they are in good agreement with the numerical simulations and their better circular symmetry indicates a clear improvement in the manufacturing process, as compared to a previous study. The low order optical modes can be reconstructed by combining the 25 influence functions; a regularization technique is used to alleviate the ill-conditioning of the Jacobian and allow to approximate the optical modes with reasonable voltages.

scholarly journals Electrostrictive PVDF-TrFE Thin Film Actuators for the Control of Adaptive Thin Shell Reflectors

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 53
Author(s):  
Kainan Wang ◽  
Thomas Godfroid ◽  
Damien Robert ◽  
André Preumont
Keyword(s):  
Piezoelectric Coefficient ◽  
Active Material ◽  
Shell Structures ◽  
Light Weight ◽  
Thin Polymer ◽  
Dynamic Experiments ◽  
Control Authority ◽  
Electrostrictive Material ◽  
Numerical Finite Element ◽  
Doubly Curved

This paper presents the technology to control the shape of thin polymer doubly curved shell structures with a unimorph layer of strain actuators to achieve high quality, light-weight, foldable space reflectors. The selected active material is PVDF-TrFE deposited by spin coating; it is electrostrictive, isotropic and enjoys an excellent piezoelectric coefficient d 31 ≃ 15 pC/N when properly annealed, but has a nonlinear, quadratic behavior. The strain actuation is controlled by an array of segmented electrodes. The purpose of this study is to evaluate the material properties achieved in the manufacturing process. A simple, unidirectional model of electrostrictive material is considered and the material constants (electrostrictive constant Q 33 , piezoelectric constant d 31 , spontaneous polarization P s and poling strain S P ) are estimated from various static and dynamic experiments. The final part of the paper illustrates the control authority on a small demonstrator with seven independent electrodes and compares the experimental results with numerical finite element simulations.

Multi-cycle reversible control of gas permeability in thin film composite membranes via efficient UV-induced reactions

2021 ◽  
Vol 57 (27) ◽  
pp. 3391-3394
Author(s):  
Abdalrahman U. Alrayyes ◽  
Ze-Xian Low ◽  
Huanting Wang ◽  
Kei Saito
Keyword(s):  
Thin Film ◽  
Polymer Coating ◽  
Gas Permeability ◽  
Composite Membranes ◽  
Polymer Structure ◽  
Film Composite ◽  
Thin Film Composite ◽  
Thin Polymer

This communication reports the use of light to reversibly constrict or ease the flow of oxygen through a very thin polymer coating. This is achievable by reversibly changing the polymer structure from a dense and rigid film to a loose and soft film.

scholarly journals Plexciton Modes Guided by an Exciton Slab in a Columnar Thin Film

2021 ◽  
Author(s):  
Mona Rostami ◽  
Ferydon Babaei
Keyword(s):  
Thin Film ◽  
Surface Plasmon ◽  
Structural Parameters ◽  
Exciton Coupling ◽  
Time Period ◽  
Surface Optical ◽  
Optical Modes ◽  
Splitting Energy ◽  
Columnar Thin Film ◽  
Plasmon Polaritons

Abstract In this study, we reported plasmon-exciton coupling for excitation the surface plexciton in columnar thin film with a central exciton slab using the transfer matrix method in Kretschmann configuration. The optical absorption spectra for surface plasmon polariton, surface exciton and surface plexciton was investigated at different structural parameters in proposed structure. The characteristics of surface optical modes were analyzed and there was an anticrossing behavior between polariton branches of plexciton spectra. Localization of surface modes on interfaces and hybridization between plasmons and excitons at both interfaces of exciton slab were proved by the time-averaged Poynting vector. We found that the types of coupling regimes between plasmons and excitons from weak to strong could be achieved. We found a high Rabi splitting energy 840 meV corresponding to the time period 5 fs which includes to the fast energy transfer between surface plasmon polaritons and surface excitons.

CRITICAL BEHAVIOUR OF FERROELECTRIC THIN FILMS

2002 ◽  
Vol 16 (03) ◽  
pp. 473-480 ◽  
Author(s):  
JULIA M. WESSELINOWA ◽  
STEFFEN TRIMPER
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Scaling Laws ◽  
Transverse Field ◽  
Ferroelectric Thin Film ◽  
Ferroelectric Thin Films ◽  
Number Of Layers ◽  
Ising Systems ◽  
2D And 3D ◽  
Good Agreement

Based on an Ising model in a transverse field (TIM) and using a Green's function formalism the critical exponents of the polarization β and of the longitudinal susceptibility γ are calculated for a ferroelectric thin film consisting of N layers. The exponents depends on the number of layers in a significant manner. Whereas for N=3 layers the exponents are β=0.131 and γ=1.739 there is a change over to β=0.315 and γ=1.239 in case of N=30. The datas are in a good agreement with predictions for 2D and 3D Ising systems. Using scaling laws other exponents like α, δ, η and ν are obtained, too.

scholarly journals Atomic Layer Deposition of NiO to Produce Active Material for Thin-Film Lithium-Ion Batteries

Coatings ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 301 ◽  
Author(s):  
Yury Koshtyal ◽  
Denis Nazarov ◽  
Ilya Ezhov ◽  
Ilya Mitrofanov ◽  
Artem Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Atomic Layer Deposition ◽  
Oxygen Plasma ◽  
Active Material ◽  
Specific Capacity ◽  
Lithium Ion ◽  
Atomic Layer ◽  
Cyclic Voltammograms ◽  
X Ray ◽  
Layer Deposition

Atomic layer deposition (ALD) provides a promising route for depositing uniform thin-film electrodes for Li-ion batteries. In this work, bis(methylcyclopentadienyl) nickel(II) (Ni(MeCp)2) and bis(cyclopentadienyl) nickel(II) (NiCp2) were used as precursors for NiO ALD. Oxygen plasma was used as a counter-reactant. The films were studied by spectroscopic ellipsometry, scanning electron microscopy, atomic force microscopy, X-ray diffraction, X-ray reflectometry, and X-ray photoelectron spectroscopy. The results show that the optimal temperature for the deposition for NiCp2 was 200–300 °C, but the optimal Ni(MeCp)2 growth per ALD cycle was 0.011–0.012 nm for both precursors at 250–300 °C. The films deposited using NiCp2 and oxygen plasma at 300 °C using optimal ALD condition consisted mainly of stoichiometric polycrystalline NiO with high density (6.6 g/cm3) and low roughness (0.34 nm). However, the films contain carbon impurities. The NiO films (thickness 28–30 nm) deposited on stainless steel showed a specific capacity above 1300 mAh/g, which is significantly more than the theoretical capacity of bulk NiO (718 mAh/g) because it includes the capacity of the NiO film and the pseudo-capacity of the gel-like solid electrolyte interface film. The presence of pseudo-capacity and its increase during cycling is discussed based on a detailed analysis of cyclic voltammograms and charge–discharge curves (U(C)).

scholarly journals Optimization of Bi2O3, TiO2, and Sb2O3Doped ZnO-Based Low-Voltage Varistor Ceramic to Maximize Nonlinear Electrical Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Masoumeh Dorraj ◽  
Azmi Zakaria ◽  
Yadollah Abdollahi ◽  
Mansor Hashim ◽  
Seyedehmaryam Moosavi
Keyword(s):  
Low Voltage ◽  
Quadratic Model ◽  
Molar Ratio ◽  
Sintering Process ◽  
Spinel Type ◽  
Factors Affecting ◽  
Milling Method ◽  
Level 3 ◽  
Central Composite ◽  
Good Agreement

In ZnO-based low voltage varistor, the two essential features of microstructure determining its nonlinear response are the formation Bi-enriched active grain boundaries as well as a controlled ZnO grain size by secondary spinel-type phases. Besides, the microstructure and phase composition are strongly affected by the dopant concentration during sintering process. In this study, the optimal dopant levels of Bi2O3, TiO2, and Sb2O3to achieve maximized nonlinear electrical property (alpha) were quantified by the response surface methodology (RSM). RSM was also used to understand the significance and interaction of the factors affecting the response. Variables were determined as the molar ratio of Bi2O3, TiO2, and Sb2O3. The alpha was chosen as response in the study. The 5-level-3-factor central composite design, with 20 runs, was used to conduct the experiments by ball milling method. A quadratic model was established as a functional relationship between three independent variables and alpha. According to the results, the optimum values of Bi2O3, TiO2, and Sb2O3were obtained 0.52, 0.50, and 0.30, respectively. Under optimal conditions the predicted alpha (9.47) was calculated using optimal coded values from the model and the theoretical value is in good agreement with the value (9.43) obtained by confirmation experiment.

Rough Surface Normal Nanocontact Stiffness: Experimental Measurements and Rough Surface Contact Model Predictions

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Jungkyu Lee ◽  
Ali Beheshti ◽  
Andreas A. Polycarpou
Keyword(s):  
Thin Film ◽  
Rough Surface ◽  
Predictive Accuracy ◽  
Contact Stiffness ◽  
Flat Punch ◽  
Surface Contact ◽  
Contact Models ◽  
Rough Surface Contact ◽  
Contact Response ◽  
Good Agreement

This work presents experimental contact stiffness measurements for various thin films as well as homogenous materials through pressing a flat punch onto a nominally flat rough surface. These materials are typically used in micro/nano technological applications with thickness of the order of few nanometers. The experimental contact stiffness results are compared with predictions by different statistical rough surface contact models to assess their predictive accuracy for thin-film applications and, in addition, to get better insight to the physics of the contact. It is observed that rough surface contact models that account for asperity interaction show good agreement with the experimental results of the thin-layered specimens contact response. This indicates the importance of accounting for asperity interaction in surface roughness contact modeling of relatively smooth thin-film materials. It is verified that interfaces with compliant films on stiff substrates as well as homogeneous materials compare relatively well with statistical models accounting for asperity interactions.

Temperature measurements in a hypersonic gun tunnel using heat-transfer methods

1967 ◽  
Vol 27 (3) ◽  
pp. 503-512 ◽  
Author(s):  
B. E. Edney
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Mach Number ◽  
Heat Losses ◽  
Transfer Rates ◽  
Gun Barrel ◽  
Compression Cycle ◽  
Initial Shock ◽  
Working Section ◽  
Good Agreement

The theory of Fay & Riddell (1958) is used to calculate stagnation temperatures from stagnation-point heat-transfer rates measured in the working section of a hypersonic gun tunnel at a Mach number of 9·8. Measurements using both thin-film gauges and calorimeters are described. The temperatures measured using this technique are found to be lower than predicted by Lemcke (1962) from measurements of shock strengths and final pressures in the gun barrel. This discrepancy is attributed to heat losses in the barrel during the initial shock compression cycle. A simple theory is developed to take into account these losses. There is good agreement between this theory and the experimental results.

scholarly journals Experimental and Theoretical Characterization of Thick and Thin Films for Microwave Uses on 99.6% Alumina Substrates

1983 ◽  
Vol 10 (2-3) ◽  
pp. 157-162 ◽  
Author(s):  
J. P. Ramy ◽  
R. Schnitzler ◽  
C. Thebault
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Copper Oxide ◽  
Ground Plane ◽  
Resistivity Measurement ◽  
Adhesive Layer ◽  
X Band ◽  
Quality Factor Q ◽  
Good Agreement

In a previous paper,1we showed, with a microwave quality factor (Q) measurement, that in the X band and with alumina substrates, thick film losses are not worse than thin film losses when the inks are screened then etched, and when they have copper oxide as adhesive layer and gold or copper as metal powder.Here, we extend this study to show that, our experimental results being in good agreement with theory, a simple D.C. resistivity measurement is sufficient to characterize these MIC'S metallizations and is as suitable as a microwave Q measurement. We also show that the nature of the ground plane cannot be neglected.

scholarly journals Vacuum Ultraviolet Field Emission Lamp Consisting of Neodymium Ion Doped Lutetium Fluoride Thin Film as Phosphor

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Masahiro Yanagihara ◽  
Takayuki Tsuji ◽  
Mohd Zamri Yusop ◽  
Masaki Tanemura ◽  
Shingo Ono ◽  
...  
Keyword(s):  
Thin Film ◽  
Field Emission ◽  
Vacuum Ultraviolet ◽  
Performance Enhancement ◽  
Carbon Nanofiber ◽  
Emission Spectra ◽  
Electron Emitters ◽  
Acceleration Voltage ◽  
Good Agreement ◽  
Neodymium Ion

A vacuum ultraviolet (VUV) field emission lamp was developed by using a neodymium ion doped lutetium fluoride (Nd3+ : LuF3) thin film as solid-state phosphor and carbon nanofiber field electron emitters. The thin film was synthesized by pulsed laser deposition and incorporated into the lamp. The cathodoluminescence spectra of the lamp showed multiple emission peaks at 180, 225, and 255 nm. These emission spectra were in good agreement with the spectra reported for the Nd3+ : LuF3crystal. Moreover, application of an acceleration voltage effectively increased the emission intensity. These results contribute to the performance enhancement of the lamp operating in the VUV region.

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