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.

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.

Directed Assembly of Nanoelements Using Electrostatically Addressable Templates

2005 ◽  
Vol 901 ◽  
Author(s):  
Xugang Xiong ◽  
Prashanth Makaram ◽  
Kaveh Bakhtari ◽  
Sivasubramanian Somu ◽  
Ahmed Busnaina ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electric Field ◽  
Electric Fields ◽  
Directed Assembly ◽  
Single Wall Carbon Nanotubes ◽  
Nanoparticle Assembly ◽  
Single Wall Carbon ◽  
Ac Electric Fields ◽  
Ac Electric Field ◽  
Dc Electric Field

AbstractDirected assembly of nanoparticles and single wall carbon nanotubes (SWNTs) using electrostatically addressable templates has been demonstrated. Nanoparticles down to 50 nm are assembled on the Au micro and nanowires of the templates in a DC and AC electric fields. The nanoparticles can be assembled in monolayers and thicker layers. Single wall carbon nanotubes (SWNTs) are also assembled without alignment on Au wires using the nanotemplate. As the size of the template wires is reduced to nanoscale dimensions, an AC electric field proves to be more effective for nanoparticle assembly than a DC electric field.

Gentle Dielectrophoretic Focusing of Yeast Cells in Curved Microchannels

2009 ◽  
Author(s):  
Christopher Church ◽  
Gaoyan Wang ◽  
Junjie Zhu ◽  
Tzuen-Rong Jeremy Tzeng ◽  
Xiangchun Xuan
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cell Concentration ◽  
Yeast Cells ◽  
Field Frequency ◽  
Electric Field Magnitude ◽  
Ac Electric Fields ◽  
Microfluidic Flow ◽  
Dc Electric Field ◽  
Ac Field

Focusing cells into a tight stream is usually a necessary step prior to counting, detecting and sorting them in, for example, microfluidic flow cytometers. We present herein a simple and gentle cell focusing technique in physiological solutions through a serpentine microchannel using DC-biased AC electric fields. This electrokinetic focusing eliminates sheath flows and in-channel microelectrodes. It results from the cross-stream dielectrophoretic motion of cells induced by the intrinsic channel curvatures. The effects of electric field magnitude, AC to DC electric field ratio, AC field frequency, and cell concentration on the focusing performance of yeast cells will be studied.

scholarly journals Meteor plasma trails: effects of external electric field

2009 ◽  
Vol 27 (1) ◽  
pp. 279-296 ◽  
Author(s):  
Y. S. Dimant ◽  
M. M. Oppenheim ◽  
G. M. Milikh
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Electrostatic Interaction ◽  
Geomagnetic Field ◽  
Dense Plasma ◽  
Dc Electric Field ◽  
E Region ◽  
Flow Through ◽  
Short Circuits ◽  
Meteor Plasma

Abstract. Meteoroids traversing the E-region ionosphere leave behind extended columns of elevated ionization known as the meteor plasma trails. To accurately interpret radar signals from trails and use them for diagnostics, one needs to model plasma processes associated with their structure and evolution. This paper describes a 3-D quantitative theory of the electrostatic interaction between a dense plasma trail, the ionosphere, and a DC electric field driven by an external dynamo. A simplified water-bag model of the meteor plasma shows that the highly conducting trail efficiently short-circuits the ionosphere and creates a vast region of currents that flow through and around the trail. We predict that the trail can induce electric fields reaching a few V/m, both perpendicular and parallel to the geomagnetic field. The former may drive plasma instabilities, while the latter may lead to strong heating of ionospheric electrons. We discuss physical and observational implications of these processes.

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

The Effect of Growth, Migration and Bacterial Cellulose Synthesis of Gluconacetobacter xylinus in Presence of Direct Current Electric Field Condition

2012 ◽  
Vol 550-553 ◽  
pp. 1108-1113 ◽  
Author(s):  
Lin Yan ◽  
Shi Ru Jia ◽  
Xin Tong Zheng ◽  
Cheng Zhong ◽  
Miao Liu ◽  
...  
Keyword(s):  
Electric Field ◽  
Bacterial Cellulose ◽  
Electric Fields ◽  
Direct Current ◽  
Cellulose Fiber ◽  
Sem Analysis ◽  
Cellulose Synthesis ◽  
Gluconacetobacter Xylinus ◽  
Growth State ◽  
Dc Electric Field

In this study, the movement and orientation of bacteria cells were controlled by direct current(DC) electric fields, result in altering alignment of bacterial cellulose nanofiber and further changing the 3-dimensional network structure of bacterial cellulose. A modified swarm plate assay was performed to investigate the migration of Gluconacetobacter xylinus cells which exposed in DC electric field. It suggested that the cells moved toward to negative pole and with the increasement of the electric field strength the velocity will also increase. The SEM analysis demonstrated that the cellulose fiber bundles which synthesized at 1V/cm have lager diameter and a trend toward one direction. Meanwhile the growth state of G.xylinus in the presence of DC electric field was also being observed.

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.

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