Electric field induced bandgap enlargement of S- and N-hyperdoped silicon
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In this paper, the effect of the electric field on the electronic structure of S-hyperdoped silicon and N-hyperdoped silicon is studied in detail by theory. The results show that the total bandgap initially increases and subsequently decreases with the increase of the electric field. Specifically, at an electric field of 0.1 V, the total bandgap reaches the maximum. With further increasing the electric field, the total bandgap decreases, but it is still larger than that in the absence of any electric field. The bandgap difference of the configuration in 2 × 2 × 2 supercell with and without electric field is approximately 0.2 eV. When 0.1 V of the electric field in the x and y directions is applied to the 2 × 2 × 3 supercell of the S- and N-hyperdoped silicon, the changes of the electronic structure are consistent. However, the band gap expansion is more obvious than that in the z direction electric field. While for 3 × 3 × 2 supercells of the S- and N-hyperdoped silicon, the band gap expansion is more significant under the z direction electric field than that under electric fields in the x and y directions. The difference in the bandgap variation under different directions of the electric field should be due to the direction-dependence of the impurity density in the 2 × 2 × 3 and 3 × 3 × 2 supercells. The results indicate that applying an electric field can further enlarge the bandgap of the S- and N-hyperdoped silicon and bring it closer to the optimal bandgap of an intermediate-band photovoltaic material.In the present investigation, we have studied the effect of electric field on the growth of carbon nanotubules. Different electric fields corresponding to 3, 6, 9, 15, and 21 V have been applied during the growth of the tubules. The estimate of the electric field corresponding to these voltages cannot be precisely evaluated in view of only approximately defined electrode dimensions. It has been observed that the application of electric field leads to the agglomerates (bundles) of nanotubules. The size, length, and alignment of these bundles varies with the strength of the applied electric field. The best results have been obtained with electric field corresponding to 6 V where the as-formed tubules are in parallel alignment and exist as bundles. As the electric field is increased, the alignment of tubules in the bundle becomes randomly oriented. The degree of randomness increases with increase of electric field after its optimum value corresponding to 6 V. The parallel alignment of the graphitic tubules is thought to result due to orientation of the tubule axis along the direction of the applied electric field corresponding to an optimum value (which for the present case is 6 V) of the impressed voltage.
Electrohydrodynamics
Electric flux
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Abstract Fog dissipation by charge and electric field has become a research hotspot due to its affordability and high efficiency compared with traditional technologies. However, the mechanism by which the electric field affects the temporal variation of droplet concentration is unclear. Therefore, a cylinder fog chamber with a radius of 0.15 m and a height of 1 m is established to analyze the influence of electric field on the concentration change of partially charged fog (50% of fog droplets are charged). The distribution of electric field in the fog chamber is simulated by an electrostatic model in COMSOL, and the electric field in the fog chamber is regarded as a parallel electric field. A percentage concentration α , the ratio of the real droplet concentration n, and the initial droplet concentration n 0 are introduced to describe the effects of fog dissipation. The results show that visibility can increase from 10 m to 150 m after applying the electric field. The shortest time is 12 s, which is much smaller than the natural settling time (102 s). Furthermore, α first increases, then decreases, and finally gets close to zero with electric field E regardless of the charged state (neutral or partially charged) at the beginning of applying the electric field ( t = 60 s). Besides, α without charging is smaller than that with partially charging. Finally, α decreases with electric field E regardless of the charged state at the end of the applied electric field ( t = 240 s). These findings can be explained by the relative strength of electrostatic force effect induced by the electric field on neutral and charged droplets and gravitational effect, which are quantified by the calculation analysis of various forces. The results can be used to guide and optimize the structure of experimental setups for outdoor fog dissipation in the future.
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To investigate the regulatory effects of bio-intensity electric field on the transformation of human skin fibroblasts (HSFs).
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Dynamics
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The external electric field enables separation and transport of droplets effectively in microfluidic devices. Herein, a volume-of-fluid (VOF) + level-set (LS) + smoothed physical parameters (SPP) method associated with the dynamically adaptive grid technique is extended to simulate three-dimensional leaky dielectric droplets in the electric field. The effects of electric and hydrodynamic forces on droplet behaviors are investigated. It is demonstrated that the electric force could act toward the outside or inside of a droplet and produce different droplet deformations. For the dielectrophoretic migration of droplets in the nonuniform electric field, the electric force has a dominant effect. It is found that when the electric conductivity ratio is greater than 1, an unbalanced electric force toward a stronger electric field is generated, bringing about the migration toward a stronger electric field. In contrast, when the electric conductivity ratio is smaller than 1, the unbalanced electric force direction is reversed and the droplet migrates toward a weaker electric field. The hydrodynamic force produces little promotion or hindrance to droplet migration. A greater permittivity ratio usually produces greater electric force and migration velocity. The droplet migrates along one direction in a symmetric nonuniform electric field but tends to migrate along the normal direction of electric potential profiles in an asymmetric nonuniform electric field.
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The quantitative descriptions are given to the distribution of electric potential and electric field intensity outside the conducting spheroid which is inside the uniform electric field.Its distribution of electric potential is that an electric potential of reacting doublet is superimposed on the original uniform electric field.The comparison expression of electric field intensity and electric potential leads to the mathematical expression of the electric field intensity and a detailed discussion of its distribution on the tangential and radial direction is conducted.
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Coalescence (physics)
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Pulsed DC
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In this paper, the effect of external electric field on nanobubbles adsorbed on the surface of hydrophobic particles during air flotation was studied by molecular dynamics simulations. The gas density distribution, diffusion coefficient, viscosity, and the change of the angle and number distribution of hydrogen bonds in the system with different amounts of gas molecules were calculated and compared with the results without an external electric field. The results show that the external electric field can make the size of the bubbles smaller. The diffusion coefficient of the gas increases and the viscosity of the system decreases when the external electric field is applied, which contribute to the reduction of the size of the nanobubbles. At the same time, comparing with the results under no external electric field, the angle of hydrogen bonding under the external electric field will increase, and the proportion of water molecules containing more hydrogen bonds will reduce, which further explains the reason why the external electric field reduces the viscosity. The conclusions of this paper demonstrate at the micro level that the external electric field can enhance the efficiency of air-floating technology for the separation of hydrophobic particles, which may provide meaningful theoretical guidance for the application and optimization of electric field-enhanced air-floating technology in practice.
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The domain configuration in the cub-oriented crystal of relaxor-ferroelectric PMN-PT was investigated with a polarizing microscope.The results indicated that under the positive DC electric field,the small ribbon-like domains paralleling to the electric field disappeared gradually when the intensity of electric field exceeded 2.45 kV/cm,and the new domains perpendicular to the electric field emerged near the electrode when the intensity of electric field rose to 7.15 kV/cm.Under the negative DC electric field,the ribbon-like domains grew along the electric field when the intensity of electric field exceeded 2.05 kV/cm.When the intensity of electric field reached 7.15 kV/cm,the domains paralleling to the electric field disappeared gradually and the new domains perpendicular to the electric field emerged.Under AC electric field,domains were vibrating with the frequency less than 50 Hz.
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