The effective mass, vibration and electromagnetic properties of tetragonal iron aluminide FeAl2

2021 ◽  
Vol 47 (2) ◽  
pp. 1766-1771
Author(s):  
Weina Liu ◽  
Xueyao Ren ◽  
Yanyan Shi ◽  
Youtian Niu ◽  
Meng Wang
Keyword(s):  
Effective Mass ◽  
Iron Aluminide ◽  
Electromagnetic Properties

Facet Topography and Dislocation Structure as a Possible Source for Electrical Heterogeneity in [001] TILT Bicrystals of YBa2Cu3O7-δ

1996 ◽  
Vol 54 ◽  
pp. 338-339
Author(s):  
I-Fei Tsu ◽  
D.L. Kaiser ◽  
S.E. Babcock
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Electromagnetic Properties ◽  
Length Scale ◽  
Density Values ◽  
Current Densities ◽  
Applied Fields ◽  
A Current

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.

ALCHEMI of B2-Ordered Fe50Al45Me5 alloys

1996 ◽  
Vol 54 ◽  
pp. 548-549
Author(s):  
Ian M. Anderson
Keyword(s):  
Room Temperature ◽  
Iron Aluminide ◽  
Low Density ◽  
Intermetallic Alloys ◽  
Practical Applications ◽  
Alloying Additions ◽  
Site Distribution ◽  
Good Corrosion Resistance ◽  
Room Temperature Ductility ◽  
The Matrix

B2-ordered iron aluminide intermetallic alloys exhibit a combination of attractive properties such as low density and good corrosion resistance. However, the practical applications of these alloys are limited by their poor fracture toughness and low room temperature ductility. One current strategy for overcoming these undesirable properties is to attempt to modify the basic chemistry of the materials with alloying additions. These changes in the chemistry of the material cannot be fully understood without a knowledge of the site-distribution of the alloying elements. In this paper, the site-distributions of a series of 3d-transition metal alloying additions in B2-ordered iron aluminides are studied with ALCHEMI.A series of seven alloys of stoichiometry Fe50AL45Me5, with Me = {Ti, V, Cr, Mn, Co, Ni, Cu}, were prepared with identical heating cycles. Microalloying additions of 0.2% B and 0.1% Zr were also incorporated to strengthen the grain boundaries, but these alloying additions have little influence on the matrix chemistry and are incidental to this study.

Adiabatic large polarons in anisotropic molecular crystals

2011 ◽  
Vol 35 (1) ◽  
pp. 15-27
Author(s):  
Zoran Ivić ◽  
Željko Pržulj
Keyword(s):  
Energy Transfer ◽  
Effective Mass ◽  
Molecular Crystals ◽  
Single Chain ◽  
Proper Understanding ◽  
One Dimensional ◽  
Interchain Coupling ◽  
Large Polaron ◽  
The One

Adiabatic large polarons in anisotropic molecular crystals We study the large polaron whose motion is confined to a single chain in a system composed of the collection of parallel molecular chains embedded in threedimensional lattice. It is found that the interchain coupling has a significant impact on the large polaron characteristics. In particular, its radius is quite larger while its effective mass is considerably lighter than that estimated within the one-dimensional models. We believe that our findings should be taken into account for the proper understanding of the possible role of large polarons in the charge and energy transfer in quasi-one-dimensional substances.

Nanocomposite Graphene based Tunable Absorber for Combating Electromagnetic Pollution

2019 ◽  
Vol 15 ◽  
Author(s):  
Surekha Rani ◽  
Anupma Marwaha ◽  
Sanjay Marwaha
Keyword(s):  
Reflection Coefficient ◽  
Traffic Congestion ◽  
Microwave Absorber ◽  
Electromagnetic Properties ◽  
Electric Conductor ◽  
High Frequency Structure Simulator ◽  
Bias Potential ◽  
External Bias ◽  
Tunable Microwave ◽  
Tunable Absorber

Background: Advancement in wireless communication technology has raised today’s living standards but consequently leads to the problems of electromagnetic (EM) air pollution as well as spectrum congestion particularly in radio frequency band. To overcome traffic congestion problem in lower bands, terahertz frequency bands are explored but EM pollution still persists as global issue which can be addressed by a tunable microwave absorber. At THz frequencies, 2-D nanostructured graphene has been observed to be less lossy than using other materials and further finds its most interesting applications on account of the plasmonic mode supported by graphene resulting in extreme device miniaturization. At micro and mm-waves graphene is resistive hence can be electronically controlled, ensuring its suitability for the design of tunable microwave absorber. Objective: Designing of a frequency reconfigurable or frequency tunable absorber is the prime objective of current work. Two-dimensional graphene absorber has been proposed here having inherent bandgap tunability property which means the electromagnetic properties of graphene can be controlled via varying external bias potential. Methods: The numerical modelling of graphene microwave absorber utilizing bulk graphene backed by glass and perfect electric conductor layer is reported in this paper. Finite element Method (FEM) based high frequency structure simulator (HFSS) platform is used to simulate the graphene absorber model. The whole structure is placed into a rectangular waveguide with two ports for absorber excitation. Results: The variation of electromagnetic properties of graphene absorber is achieved by changing bias potential and further the absorption tunability for the designed absorber is investigated in the range from 2 GHz to 18 GHz. From reflection coefficient curves, it is authenticated that -72.6 dB reflection coefficient dip has been obtained at 14 GHz for 5 volt bias potential which shifts to higher side of frequency as the potential changes from 5 volts to 25 volts. Conclusion: The results show that by increasing bias potential, absorption coefficient shifts to higher frequency and proves to be a tunable wideband absorber whose resonant frequency can changed from one value to another without changing thickness or material properties of absorber thus can effectively incorporate with antenna substrate or surface of radar.

Sign in / Sign up

Export Citation Format

Share Document