Electric field driven fractal growth dynamics in polymeric medium

2014 ◽  
Vol 378 (40) ◽  
pp. 2951-2958 ◽  
Author(s):  
Anit Dawar ◽  
Amita Chandra
Keyword(s):  
Electric Field ◽  
Growth Dynamics ◽  
Fractal Growth ◽  
Polymeric Medium

Spatiotemporal characterization of the field-induced insulator-to-metal transition

Science ◽  
2021 ◽  
pp. eabd9088
Author(s):  
Javier del Valle ◽  
Nicolas M. Vargas ◽  
Rodolfo Rocco ◽  
Pavel Salev ◽  
Yoav Kalcheim ◽  
...  
Keyword(s):  
Electric Field ◽  
Time Resolution ◽  
Growth Dynamics ◽  
Metallic Phase ◽  
Resistivity Change ◽  
Filament Formation ◽  
Correlated Systems ◽  
In Operando ◽  
Crucial Parameter

Many correlated systems feature an insulator-to-metal transition that can be triggered by an electric field. Although it is known that metallization takes place through filament formation, the details of how this process initiates and evolves remain elusive. We use in-operando optical reflectivity to capture the growth dynamics of the metallic phase with space and time resolution. We demonstrate that filament formation is triggered by nucleation at hotspots, with a subsequent expansion over several decades in time. By comparing three case studies (VO2, V3O5 and V2O3), we identify the resistivity change across the transition as the crucial parameter governing this process. Our results provide a spatiotemporal characterization of volatile resistive switching in Mott insulators, key for emerging technologies such as optoelectronics or neuromorphic computing.

Electrowetting-Based Coalescence of Droplets During Dropwise Condensation of Humid Air

2019 ◽  
Author(s):  
Enakshi Wikramanayake ◽  
Vaibhav Bahadur
Keyword(s):  
Heat Transfer ◽  
Electric Field ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Growth Dynamics ◽  
Condensation Heat Transfer ◽  
Droplet Growth ◽  
Dropwise Condensation ◽  
Condensation Rate ◽  
Humid Air

Abstract Dropwise condensation yields higher heat transfer coefficients by avoiding the thermal resistance of the condensate film, seen during filmwise condensation. This work explores further enhancement of dropwise condensation heat transfer through the use of electrowetting to achieve faster droplet growth via coalescence of the condensed droplets. Electrowetting is a well understood microfluidic technique to actuate and control droplets. This work shows that AC electric fields can significantly enhance droplet growth dynamics. This enhancement is a result of coalescence triggered by various types of droplet motion (translation of droplets, oscillations of three phase line), which in turn depends on the frequency of the applied AC waveform. The applied electric field modifies droplet condensation patterns as well as the roll-off dynamics on the surface. Experiments are conducted to study early-stage droplet growth dynamics, as well as steady state condensation rates under the influence of electric fields. It is noted that this study deals with condensation of humid air, and not pure steam. Results show that increasing the voltage magnitude and frequency increases droplet growth rate and overall condensation rate. Overall, this study reports more than a 30 % enhancement in condensation rate resulting from the applied electric field, which highlights the potential of this concept for condensation heat transfer enhancement.

Fractal Growth of Minerals: a Modified DLA Model

2011 ◽  
Vol 239-242 ◽  
pp. 1470-1473 ◽  
Author(s):  
Yan Shi Xie ◽  
Cai Rong Tu ◽  
Kai Xuan Tan ◽  
Liang Chen
Keyword(s):  
Three Dimensional ◽  
Growth Dynamics ◽  
Attraction Domain ◽  
Square Lattice ◽  
Gradual Transition ◽  
Confined Space ◽  
Fractal Growth ◽  
Model Sets ◽  
Growth System ◽  
Dimensional Simulation

A modified fractal growth model of minerals was considered in the square lattice 300 × 300. One seed is placed at the center of the square lattice as a growth focus and the attraction domain is set to diamond. Three main parameters are considered in this model which probability of the surface adhesion is Pg with the range of 0 to 99% to eliminate the noise impact and adsorption distance d varies from 0 to 9 units on behalf of the gravitational field strength between particles and fill gaps s varied from 0.00 to 5.00 units distance to perform the influence of environmental temperature on the minerals growth system. Three model sets are carried out with two fixed parameters and the other changed parameter. The results show the fractal dimension of DLA group increase with the decrease of Pg and the increases of d and s, as well as the structure of minerals from disseminated, star or radial gradual transition to agglomerate. The model is a two-dimensional simulation for three-dimensional fractal growth and can not fully reflect the complex growth dynamics of mineral aggregate in three-dimensional confined space.

Strongly electric-field-dependent spatial properties of fanning beam in polymeric medium

2005 ◽  
Vol 86 (8) ◽  
pp. 084103 ◽  
Author(s):  
Takafumi Sassa ◽  
Tsuyoshi Muto ◽  
Tatsuo Wada ◽  
Yosuke Takeda ◽  
Takashi Fujihara ◽  
...  
Keyword(s):  
Electric Field ◽  
Spatial Properties ◽  
Field Dependent ◽  
Polymeric Medium

Electric-field assisted nucleation processes of croconic acid films

CrystEngComm ◽  
2019 ◽  
Vol 21 (48) ◽  
pp. 7460-7467 ◽  
Author(s):  
Yifan Yuan ◽  
Xuanyuan Jiang ◽  
Shashi Poddar ◽  
Xiaoshan Xu
Keyword(s):  
Electric Field ◽  
Temperature Dependence ◽  
External Electric Field ◽  
Nucleation Rate ◽  
Heterogeneous Nucleation ◽  
Growth Dynamics ◽  
Nucleation Process

An external electric field can affect the growth dynamics of croconic acid (CA) films, especially the heterogeneous nucleation process, as evidenced by the shift of temperature dependence of the nucleation rate in the electric field.

Resolution in photoelectron microscopy

1991 ◽  
Vol 49 ◽  
pp. 458-459
Author(s):  
G. F. Rempfer
Keyword(s):  
Electron Microscopy ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Uniform Field ◽  
Virtual Image ◽  
Lens System ◽  
Photoemission Electron Microscopy ◽  
Planar Electrode ◽  
Electron Lens ◽  
Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

Cristal-growth dynamics of n-doped gaAs

1992 ◽  
Vol 50 (2) ◽  
pp. 1544-1545
Author(s):  
Pham V. Huong ◽  
Stéphanie Bouchet ◽  
Jean-Claude Launay
Keyword(s):  
Crystal Growth ◽  
Spatial Resolution ◽  
Epitaxial Layer ◽  
Outer Surface ◽  
Gaas Substrate ◽  
Structural Modification ◽  
Growth Dynamics ◽  
Argon Laser ◽  
High Anisotropy ◽  
Crystal Gaas

Microstructure of epitaxial layers of doped GaAs and its crystal growth dynamics on single crystal GaAs substrate were studied by Raman microspectroscopy with a Dilor OMARS instrument equipped with a 1024 photodiode multichannel detector and a ion-argon laser Spectra-Physics emitting at 514.5 nm.The spatial resolution of this technique, less than 1 μm2, allows the recording of Raman spectra at several spots in function of thickness, from the substrate to the outer deposit, including areas around the interface (Fig.l).The high anisotropy of the LO and TO Raman bands is indicative of the orientation of the epitaxial layer as well as of the structural modification in the deposit and in the substrate at the interface.With Sn doped, the epitaxial layer also presents plasmon in Raman scattering. This fact is already very well known, but we additionally observed that its frequency increases with the thickness of the deposit. For a sample with electron density 1020 cm-3, the plasmon L+ appears at 930 and 790 cm-1 near the outer surface.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

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