scholarly journals Electrical Behavior and Microstructural Features of Electric Field-Assisted and Conventionally Sintered 3 mol% Yttria-Stabilized Zirconia

Ceramics ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Sabrina Carvalho ◽  
Eliana Muccillo ◽  
Reginaldo Muccillo
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Vacancy Concentration ◽  
Chemical Species ◽  
Oxygen Vacancy Concentration ◽  
Electrical Behavior ◽  
Boundary Conductivity ◽  
Ac Electric Fields ◽  
Ac Current ◽  
Field Assisted Sintering

ZrO2: 3 mol% Y2O3 (3YSZ) polycrystalline pellets were sintered at 1400 °C and by applying an alternating current (AC) electric field at 1000 °C. An alumina sample holder with platinum wires for connecting the sample to a power supply was designed for the electric field-assisted sintering experiments. The apparent density was evaluated with the Archimedes technique, the grain size distribution by analysis of scanning electron microscopy images, and the electrical behavior by the impedance spectroscopy technique. Sintering with the application of AC electric fields to 3YSZ enhances its ionic conductivity. An explanation is proposed, based on the dissolution back to the bulk of chemical species, which are depleted at the grain boundaries, leading to an increase in the oxygen vacancy concentration. For the enhancement of the grain boundary conductivity, an explanation is given based on the diminution of the concentration of depleted chemical species, which migrate to the bulk. This migration leads to a decrease of the potential barrier of the space charge region, known to be responsible for blocking the oxide ions through the intergranular region. Moreover, the heterogeneity of the distribution of the grain sizes is ascribed to the skin effect, the tendency of the AC current density to be largest near the surface, decreasing towards the bulk.

Effect of Microstructure on Lifetime Performance of Barium Titanate Ceramics Under DC and AC Electric Fields

2010 ◽  
Author(s):  
Jay Shieh
Keyword(s):  
Fatigue Strength ◽  
Barium Titanate ◽  
Electric Field ◽  
Electric Fields ◽  
Time To Failure ◽  
Electrical Loading ◽  
Ac Electric Fields ◽  
Lifetime Performance ◽  
Weibull Statistical Analysis ◽  
Dc Electric Field

Bulk barium titanate (BaTiO3 ) ceramic specimens with bimodal microstructures are prepared and their dielectric and fatigue strengths are investigated under an alternating current (AC) electric field and a direct current (DC) electric field. It is found that under AC electrical loading, both the dielectric and fatigue strengths decrease with increasing amount of coarse abnormal grains. The scatter of the AC fatigue strength is characterized with the Weibull statistics. The extent of scatter of the AC fatigue strength data correlates strongly with the size distribution of the coarse grains. Such correlation is resulted from the presence of intrinsic defects within the microstructure. For DC electrical loading, the time to failure of the specimens with coarse abnormal grains is significantly shorter than the lifetimes of the specimens with only small normal grains. It is found that under a DC electric field of 6 MVm−1, the BaTiO3 specimens would fail within 200 h when abnormal grains are present in the microstructure. However, the lifetimes of the specimens containing abnormal grains vary significantly from one to another. The Weibull statistical analysis indicates that the amount of abnormal grains has little influence on the lifetime performance of bulk BaTiO3 ceramics under large DC electric fields. In most of the failed BaTiO3 specimens under DC electrical loading, regardless of their lifetimes, large through-thickness round holes with recrystallization features are present. A mixed failure mode consisting of avalanche and thermal breakdowns is proposed for the failed specimens.

Electric Conductance

1997 ◽  
Author(s):  
C. B. Li
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Colloidal Particles ◽  
Free Solution ◽  
Soil Particles ◽  
Electric Conductance ◽  
Variable Charge ◽  
Ac Electric Fields ◽  
The Difference ◽  
Variable Charge Soils

The migration of colloidal soil particles in an applied electric field has been discussed in Chapter 7. Soil particles carrying electric charges invariably adsorb equivalent amounts of ions of the opposite charge. Generally there is a certain amount of free ions present in soil solution. When an electric field is applied to a soil system, a phenomenon known as electric conductance occurs. As in the case for electrolyte solutions, soil particles and various ions interact with one another during their migration, and these interactions can affect the electric conductance of the system. Variable charge soils carry both positive and negative surface charges, and it can be expected that their interactions with various ions would be rather complicated during conductance. On the other hand, this makes the measurement of electric conductance an effective means in elucidating the mechanisms of interactions between variable charge soils and ions. Both direct-current (DC) electric fields and alternating-current (AC) electric fields can induce the migration of charged particles. In the latter case, the migration of these particles should be related to the frequency of the applied AC electric field. Therefore, in this chapter, after describing the principles of electric conductance of ions and colloids and the factors that affect the conductance of a soil, emphasis shall be placed on the interaction between variable charge soils and various ions as reflected by the frequency effect in electric conductance. For a colloidal suspension, the electric conductance may be regarded as the contribution of conductances of both charged colloidal particles and ions. These two parts may be called the electric conductance of colloidal panicles and the electric conductance of ions, respectively. However, in actual cases it is difficult to distinguish between these two parts. Therefore, it is a general practice to distinguish the electric conductance as that caused by colloidal particles plus their counterions from that caused by ions of the free solution. These may be called electric conductance of the colloid and electric conductance of the free solution. The former conductance is the difference between the electric conductance of the suspension and that of the free solution.

Dynamic Electromechanical Response of Multilayered Piezoelectric Composites From Room to Cryogenic Temperatures for Fuel Injector Applications

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Yasuhide Shindo ◽  
Takayoshi Sasakura ◽  
Fumio Narita
Keyword(s):  
Domain Wall ◽  
Electric Field ◽  
Electric Fields ◽  
Wall Motion ◽  
Domain Wall Motion ◽  
Cryogenic Temperatures ◽  
Fuel Injector ◽  
Temperature Dependent ◽  
Piezoelectric Composites ◽  
Ac Electric Fields

This paper studies the dynamic electromechanical response of multilayered piezoelectric composites under ac electric fields from room to cryogenic temperatures for fuel injector applications. A shift in the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral/monoclinic phases with decreasing temperature was determined using a thermodynamic model, and the temperature dependent piezoelectric coefficients were obtained. Temperature dependent coercive electric field was also predicted based on the domain wall energy. A phenomenological model of domain wall motion was then used in a finite element computation, and the nonlinear electromechanical fields of the multilayered piezoelectric composites from room to cryogenic temperatures, due to the domain wall motion and shift in the MPB, were calculated. In addition, experimental results on the ac electric field induced strain were presented to validate the predictions.

Modeling of Nanoparticle-Mediated Electric Field Enhancement Inside Biological Cells Exposed to AC Electric Fields

2009 ◽  
Vol 48 (8) ◽  
pp. 087001 ◽  
Author(s):  
Pawan K. Tiwari ◽  
Sung Kil Kang ◽  
Gon Jun Kim ◽  
Jun Choi ◽  
A.-A. H. Mohamed ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Field Enhancement ◽  
Biological Cells ◽  
Electric Field Enhancement ◽  
Ac Electric Fields

UNDERSTANDING ELECTRIC INTERACTIONS IN SUSPENSIONS IN GRADIENT AC ELECTRIC FIELDS I: EXPERIMENTAL

2011 ◽  
Vol 25 (07) ◽  
pp. 919-925
Author(s):  
YAN SHEN ◽  
ZHIYONG QIU ◽  
SHIGERU TADA
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Corn Oil ◽  
Electrode Array ◽  
Ac Electric Fields ◽  
Ac Electric Field ◽  
Alpha Olefin ◽  
Dilute Suspensions ◽  
Spatially Periodic ◽  
Neutrally Buoyant

When neutrally buoyant poly alpha olefin particles in corn oil were exposed to a gradient ac electric field generated by a spatially periodic electrode array, these particles experienced the negative dielectrophoresis and instability in all the suspensions of concentration range from 0.01% to 5% (v/v). One critical particle concentration was experimentally determined as 1% (v/v) below which the particles in corn oil were segregated to form island-like structures in the lower electric field regions; and above which, particles only formed straight stripes. The island-like structure was suspended in the lowest electric field area. Specially designed experiments with a suspension of 1.126% (v/v) confirmed that there exists particle instability. Anisotropic properties of electric interactions are responsible for particle instability in all the suspensions of different concentrations and island-like structures were formed only in the dilute suspensions in which the particle instability has enough space to be developed.

Precise morphology control and fast merging of a complex multi-emulsion system: the effects of AC electric fields

Soft Matter ◽  
2019 ◽  
Vol 15 (28) ◽  
pp. 5614-5625 ◽  
Author(s):  
Yi Huang ◽  
Shuai Yin ◽  
Wen Han Chong ◽  
Teck Neng Wong ◽  
Kim Tiow Ooi
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Morphology Control ◽  
Emulsion System ◽  
Contact Type ◽  
Ac Electric Fields ◽  
Ac Electric Field

We showed a full morphology control over complex emulsions through an AC electric field by non-contact type of electrodes.

Pyroelectricity versus conductivity in soft lead zirconate titanate (PZT) ceramics

2007 ◽  
Vol 22 (12) ◽  
pp. 3448-3454 ◽  
Author(s):  
Talal M. Kamel ◽  
G. de With
Keyword(s):  
Electric Fields ◽  
Lead Zirconate Titanate ◽  
Room Temperature ◽  
Vacancy Concentration ◽  
Lead Zirconate ◽  
Pyroelectric Coefficient ◽  
Displacement Current ◽  
Electrical Behavior ◽  
Pzt Ceramics ◽  
Zirconate Titanate

The electrical behavior of modified soft lead zirconate titanate (PZT) ceramics has been studied as a function of temperature at different direct current (dc) electric fields and grain sizes. As ferroelectrics, such as PZT, are highly polarizable materials, poling, depolarization, and electric conduction contribute to the total electrical current, which leads to anomalous electrical behavior as a function of temperature. The PZT appeared to have a high pyroelectric coefficient, and it was found that the displacement current hides the conduction current near room temperature. The (long-time) steady-state electrical resistivity of the soft PZT used has a typical, relatively high value of 3.6 × 1012 Ω·cm near room temperature. The resistivity above the Curie temperature was two orders of magnitude lower than the room temperature. The resistivity decreases with increasing grain size probably due to the increased Pb vacancy concentration resulting as a consequence of a higher sintering temperature. The values of activation energies suggest that the charge carriers at high temperature are mainly oxygen vacancies. At intermediate temperature, the electrical behavior is controlled by the counteracting effect of depolarization and conduction. Considering the pyroelectric effect and the conduction, it was thus possible to explain the electrical behavior of this soft PZT ceramic over the temperature range considered.

scholarly journals In-flight calibration of double-probe DC electric field measurements on Cluster

2014 ◽  
Vol 4 (1) ◽  
pp. 85-107
Author(s):  
Y. V. Khotyaintsev ◽  
P.-A. Lindqvist ◽  
C. M. Cully ◽  
A. I. Eriksson ◽  
M. André
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Field Measurements ◽  
Calibration Procedure ◽  
Double Probe ◽  
Ac Electric Fields ◽  
Dc Electric Field ◽  
Electric Field Measurements

Abstract. Double-probe electric field instrument with long wire booms is one of the most popular techniques for in situ measurement of DC and AC electric fields in plasmas on spinning spacecraft platforms, which have been employed on a large number of space missions. Here we present an overview of the calibration procedure used for the EFW instrument on Cluster, which involves spin fits of the data and correction of several offsets. We also describe the procedure for the offset determination and present results for the long-term evolution of the offsets.

scholarly journals Reaction-free concentration gradient generation in spatially non-uniform AC electric fields

2022 ◽  
Author(s):  
Ran An ◽  
Adrienne Minerick
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Concentration Gradient ◽  
Electrochemical Techniques ◽  
Hafnium Dioxide ◽  
Ion Concentration ◽  
Concentration Gradients ◽  
Free Concentration ◽  
Bulk Fluid ◽  
Ac Electric Fields

The ability to generate stable, spatiotemporally controllable concentration gradients is critical for both electrokinetic and biological applications such as directional wetting and chemotaxis. Electrochemical techniques for generating solution and surface gradients display benefits such as simplicity, controllability, and compatibility with automation. Here, we present an exploratory study for generating micro-scale spatiotemporally controllable gradients using a reaction-free electrokinetic technique in a microfluidic environment. Methanol solutions with ionic Fluorescein isothiocyanate (FITC) molecules were used as an illustrative electrolyte. Spatially non-uniform alternating current (AC) electric fields were applied using hafnium dioxide (HfO2) coated Ti/Au electrode pairs. Results from spatial and temporal analysis, along with control experiments suggest that the FITC ion concentration gradient in bulk fluid (over 50 µm from the electrode) was established due to spatial variation of electric field density, and was independent of electrochemical reactions at the electrode surface. The established ion concentration gradients depended on both amplitudes and the frequencies of the oscillating AC electric field. Overall, this work reports a novel approach for generating stable and spatiotemporally tunable gradients in a microfluidic chamber using a reaction-free electrochemical methodology.

HYSTERESIS EFFECT OF SINGLE DOUBLE-END ANCHORED POLYELECTROLYTE IN AC ELECTRIC FIELD

2012 ◽  
Vol 26 (14) ◽  
pp. 1250089 ◽  
Author(s):  
QI-YI ZHANG ◽  
XUN XIANG ◽  
KAI-YAN HU
Keyword(s):  
Electric Field ◽  
Chain Length ◽  
Electric Fields ◽  
Characteristic Frequency ◽  
Brownian Dynamics ◽  
Mode Analysis ◽  
Ac Electric Fields ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations ◽  
Field Plane

We investigate the dynamics of a single flexible and semiflexible polyelectrolyte (PE) chain, fixed at both ends under the action of spatially uniform alternating-current (AC) electric fields using Brownian dynamics simulations. The results show that the shapes of the orbits in the position-electric field plane are strongly influenced by the factors such as the frequencies of the AC electric fields, the whole chain length, the pinned chain length, the friction coefficient of polymer beads and the elasticity constant of polymer chain. These orbits transform from hysteretic cycles to single curves when the frequencies are smaller than the characteristic frequency ω*. The influences of the above factors on ω* have been explored. The physical mechanism and the values of the characteristic frequency have been explored in detail within the Rouse-mode analysis. The values of ω* can be roughly predicted from Rouse-mode analysis.

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