Ac electrical conductivity and magnetic properties of BiFeO3–CoFe2O4 nanocomposites

2014 ◽  
Vol 599 ◽  
pp. 32-39 ◽  
Author(s):  
H.B. Sharma ◽  
K. Nomita Devi ◽  
V. Gupta ◽  
J.H. Lee ◽  
S. Bobby Singh
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Properties ◽  
Ac Electrical Conductivity

Temperature dependence of the transient and AC electrical conductivity of porous silicon thin films

2003 ◽  
Vol 101 (1-3) ◽  
pp. 334-337 ◽  
Author(s):  
M. Theodoropoulou ◽  
C.A. Krontiras ◽  
N. Xanthopoulos ◽  
S.N. Georga ◽  
M.N. Pisanias ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Porous Silicon ◽  
Temperature Dependence ◽  
Ac Electrical Conductivity ◽  
Silicon Thin Films

The ac electrical conductivity for Co-substituted SbNi ferrites

1996 ◽  
Vol 152 (3) ◽  
pp. 391-395 ◽  
Author(s):  
M.A. Ahmed ◽  
M.A. El Hiti ◽  
M.K. El Nimr ◽  
M.A. Amer
Keyword(s):  
Electrical Conductivity ◽  
Ac Electrical Conductivity

scholarly journals Effects of Frequency and Temperature on Electric Field Mitigation Method via Protruding Substrate Combined with Applying Nonlinear FDC Layer in Wide Bandgap Power Modules

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2022 ◽  
Author(s):  
Maryam Mesgarpour Tousi ◽  
Mona Ghassemi
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Metal Layer ◽  
Wide Bandgap ◽  
High Density ◽  
Field Calculation ◽  
Power Module ◽  
Temperature Dependent ◽  
Ac Electrical Conductivity ◽  
Power Modules

Our previous studies showed that geometrical techniques including (1) metal layer offset, (2) stacked substrate design and (3) protruding substrate, either individually or combined, cannot solve high electric field issues in high voltage high-density wide bandgap (WBG) power modules. Then, for the first time, we showed that a combination of the aforementioned geometrical methods and the application of a nonlinear field-dependent conductivity (FDC) layer could address the issue. Simulations were done under a 50 Hz sinusoidal AC voltage per IEC 61287-1. However, in practice, the insulation materials of the envisaged WBG power modules will be under square wave voltage pulses with a frequency of up to a few tens of kHz and temperatures up to a few hundred degrees. The relative permittivity and electrical conductivity of aluminum nitride (AlN) ceramic, silicone gel, and nonlinear FDC materials that were assumed to be constant in our previous studies, may be frequency- and temperature-dependent, and their dependency should be considered in the model. This is the case for other papers dealing with electric field calculation within power electronics modules, where the permittivity and AC electrical conductivity of the encapsulant and ceramic substrate materials are assumed at room temperature and for a 50 or 60 Hz AC sinusoidal voltage. Thus, the big question that remains unanswered is whether or not electric field simulations are valid for high temperature and high-frequency conditions. In this paper, this technical gap is addressed where a frequency- and temperature-dependent finite element method (FEM) model of the insulation system envisaged for a 6.5 kV high-density WBG power module will be developed in COMSOL Multiphysics, where a protruding substrate combined with the application of a nonlinear FDC layer is considered to address the high field issue. By using this model, the influence of frequency and temperature on the effectiveness of the proposed electric field reduction method is studied.

scholarly journals Electrical Current Map and Bulk Conductivity of Carbon Fiber-Reinforced Nanocomposites

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1865 ◽  
Author(s):  
Liberata Guadagno ◽  
Luigi Vertuccio ◽  
Carlo Naddeo ◽  
Marialuigia Raimondo ◽  
Giuseppina Barra ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fiber ◽  
Electrical Current ◽  
Bulk Conductivity ◽  
Fiber Reinforced ◽  
Electrical Stability ◽  
Flame Resistance ◽  
Ac Electrical Conductivity ◽  
Multi Wall Carbon Nanotubes ◽  
Carbon Fiber Reinforced

A suitably modified resin film infusion (RFI) process was used for manufacturing carbon fiber-reinforced composites (CFRCs) impregnated with a resin containing nanocages of glycidyl polyhedral oligomeric silsesquioxane (GPOSS) for enhancing flame resistance and multi-wall carbon nanotubes (MWCNTs) to contrast the electrical insulating properties of the epoxy resin. The effects of the different numbers (7, 14 and 24) of the plies on the equivalent direct current (DC) and alternating current (AC) electrical conductivity were evaluated. All the manufactured panels manifest very high values in electrical conductivity. Besides, for the first time, CFRC strings were analyzed by tunneling atomic force microscopy (TUNA) technique. The electrical current maps highlight electrically conductive three-dimensional networks incorporated in the resin through the plies of the panels. The highest equivalent bulk conductivity is shown by the seven-ply panel characterized by the parallel (σ//0°) in-plane conductivity of 16.19 kS/m. Electrical tests also evidence that the presence of GPOSS preserves the AC electrical stability of the panels.

Cation Conductivity in Mixed Sulfate-Based and Mixed Iodide-Based Solids with Phase Transitions

1994 ◽  
Vol 369 ◽  
Author(s):  
E. A. Secco
Keyword(s):  
Electrical Conductivity ◽  
Phase Transitions ◽  
Temperature Dependence ◽  
Ionic Radius ◽  
Ion Conductivity ◽  
Ac Electrical Conductivity ◽  
Cation Conductivity ◽  
Fast Ion ◽  
Contribution Limits

AbstractThe ac electrical conductivity versus temperature dependence of solids undergoing phase transitions incorporating various guest ions, viz isovalent cations and anions, ions with different ionic radius, ions with different polarizability, in Na2SO4-based, Ag2SO4-based, Li2SO4-based and U02SO4-based compositions along with MxTl(1x)I compositions for 1 ≤ x ≤ 0.13, whose M = K, Rb, Cs, are reported. An overview is given of the interplay of various factors, structural and non-structural, with their contribution limits impacting on locking-in the fast cation conductivity phase and the interpretation of fast-ion conductivity in the context of a percolation-type of ionstransport mechanism.

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