Electric-Field-Triggered Graphene Production: From Fundamental Energy Applications to Perspectives

We have theoretically obtained the transmittance properties of one-dimensional phononic crystals incorporating a piezoelectric material as a defect layer. We have used the transfer matrix method in our analysis with/without defect materials. By increasing the thickness of the defect layer, we obtained a sharp peak created within the bandgap, that indicates to the significance of defect layer thickness on the band structure. The localized modes and a particular intensity estimated within the bandgap depend on the piezoelectric material properties. By applying different quantities of an external electric field, the position of the peak shifts to different frequencies. The electric field induces a relative change in the piezoelectric thickness. Our structure may be very useful in some applications such as sensors, acoustic switches, and energy applications.

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Unraveling Dielectric Abnormality Based on the Effect of Defect Dipoles in Cr Ion Doped Multipurpose Properties of BCT Ceramics

10.21203/rs.3.rs-113349/v1 ◽

2020 ◽

Author(s):

Preeti Redhu ◽

Preeti Sharma ◽

Rajesh Punia ◽

Anupinder Singh ◽

Anil Ohlan ◽

...

Keyword(s):

Energy Storage ◽

Magnetic Fields ◽

Electric Field ◽

Room Temperature ◽

Room Temperature Ferromagnetism ◽

Solid State Reaction Method ◽

Calcium Titanate ◽

Low Frequencies ◽

Energy Applications ◽

Free Material

Abstract With the motive of unraveling the effect of Cr incorporation on the structural, microstructural, dielectric, ferroelectric, energy storage, and magnetic properties of BCT (Barium Calcium Titanate) ceramics have been investigated. Ba0.80Ca0.20Ti1-3x/4CrxO3 (0.000 ≤ x ≤ 0.020) powder samples have been prepared using classical solid-state reaction method. Cr doped BCT ceramics showed a single phase perovskite structure having a tetragonal phase without phase transformation from P4mm to Pm-3m after the addition of Cr. With increased Cr content, the tolerance factor, lattice parameters, unit cell volume, c\a ratio, and grain size have been found to decrease. Both Debye-Scherrer and Williamson-Hall plot methods confirmed the reduction of crystallite size on increased Cr doping in BCT lattice. A dielectric anomaly “hump” (̴ 447 K) has been observed at low frequencies in the paraelectric region due to the presence of acceptor induced defect dipoles. The temperature-dependent dielectric properties of prepared BCT ceramic with Cr compositions possess diffused phase transition (DPT) and the width of DPT is increased. Room temperature energy storage density achieved the maximum value of 190.35 mJ/cm3 for the composition x = 0.005 at an electric field of 55 kV/cm. For the Cr composition of x = 0.015 and an electric field of 10 kV/cm, the highest energy storage efficiency (η) of about 60.5 % has been obtained at room temperature. % Temperature coefficient of capacitance has been obtained to vary between ± 15 % in the temperature range of 303 K to 523 K. Cr doped ceramic samples exhibit room temperature ferromagnetism at low magnetic fields and diamagnetism at a higher value of magnetic fields. These results suggest prepared ceramics as a suitable lead-free material for X8R multilayer ceramic capacitor devices and energy applications.

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Resolution in photoelectron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086593 ◽

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.

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Field-assisted ionization theory for microscopists

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171833 ◽

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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