scholarly journals Formation of grain boundary second phase in BaTiO3 polycrystal under a high DC electric field at elevated temperatures

2016 ◽  
Vol 124 (4) ◽  
pp. 388-392 ◽  
Author(s):  
Hidehiro YOSHIDA ◽  
Akinori UEHASHI ◽  
Tomoharu TOKUNAGA ◽  
Katsuhiro SASAKI ◽  
Takahisa YAMAMOTO
Keyword(s):  
Grain Boundary ◽  
Electric Field ◽  
Elevated Temperatures ◽  
Second Phase ◽  
Dc Electric Field

scholarly journals Grain Boundary Resistivity of Yttria-Stabilized Zirconia at 1400°C

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
J. Wang ◽  
A. Du ◽  
Di Yang ◽  
R. Raj ◽  
H. Conrad
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Electric Field ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Brick Layer Model ◽  
Dc Electric Field ◽  
Lower Temperature ◽  
Boundary Width ◽  
Grain Boundary Resistivity

The grain size dependence of the bulk resistivity of 3 mol% yttria-stabilized zirconia at 1400°C was determined from the effect of a dc electric field Ea=18.1 V/cm on grain growth and the corresponding electric current during isothermal annealing tests. Employing the brick layer model, the present annealing test results were in accordance with extrapolations of the values obtained at lower temperature employing impedance spectroscopy and 4-point-probe dc. The combined values give that the magnitude of the grain boundary resistivity ρb=133 ohm-cm. The electric field across the grain boundary width was 28–43 times the applied field for the grain size and current ranges in the present annealing test.

Chemical-Demulsifier Development Based on Critical-Electric-Field Measurements

SPE Journal ◽  
2008 ◽  
Vol 13 (03) ◽  
pp. 346-353 ◽  
Author(s):  
Jan H. Beetge ◽  
Bruce Horne
Keyword(s):  
Electric Field ◽  
Crude Oil ◽  
Elevated Temperatures ◽  
Emulsion Stability ◽  
Critical Voltage ◽  
Crude Oils ◽  
Second Phase ◽  
Oil Emulsion ◽  
Oil Emulsions ◽  
Water In Oil Emulsion

Summary Resolution of water-and-oil emulsions is critical to the oilfield industry. A wide variety of undesirable emulsions are formed during the production, handling, and processing of crude oil. Although various methods are used, dehydration of crude oils is achieved mostly by gravitational sedimentation, normally at elevated temperatures and with the addition of chemical demulsifiers. The quantitative evaluation of emulsion stability by a critical-electric-field (CEF) technique was developed to play a significant role in chemical-demulsifier research. It was found that the CEF technique is useful not only in the evaluation of water-in-oil-emulsion stability, but also in studying the mechanisms of stabilization and demulsification. A method was developed to study the mechanism of emulsion stabilization in terms of flocculation and coalescence behavior of a crude-oil emulsion. The effect of chemical demulsifiers on emulsion stability was evaluated in terms of the method developed in this study. By following this approach, it is possible to determine the relative amount of energy required for both flocculation and coalescence in the presence of a chemical demulsifier. Introduction The inevitable creation and subsequent resolution of water-in-oil emulsions during the production and processing of crude oils are of significant importance in the oilfield industry. These emulsions, which typically could be any combination of water-in-oil, oil-in-water, or complex emulsions, are diverse in their nature and stability. The majority of oilfield emulsions are resolved by the application of chemical demulsifiers in special processes under specific conditions. The stability of crude-oil emulsions is influenced by many variables; therefore, and chemical demulsifiers are developed specifically for each application to achieve optimum economic efficiency. Emulsion stability of water-in-oil emulsions encountered in the oilfield industry can be evaluated with various methods (e.g., determining droplet size and distribution, determining the amount of water resolved as a second phase, analyzing moisture of the oil phase, and more-sophisticated methods such as interfacial rheology). Sullivan et al. (2004) suggested the use of CEF as a method to provide information for stability-correlation development. Commercial separation of a dispersed aqueous phase from typical crude oil by electrostatic methods is well-known and dates to the early 20th century (Cottrell 1911; Cottrell and Speed 1911). Electrostatic dehydration technology is still being developed and refined to play an important role in challenging oilfield applications (Warren 2002). The use of CEF, as a method to evaluate water-in-oil-emulsion stability, has been developed recently by Kilpatrick et al. (2001). In their CEF technique, a sample of water-in-oil emulsion is injected between two parallel electrode plates. A direct-current voltage is applied between the two electrodes and is increased in incremental steps, with continuous monitoring of the conductivity or the amount of electrical current through the oil sample. Fig. 1 shows a simple diagram of the CEF technique. In response to the increasing applied electric field, the water droplets tend to align themselves to form agglomerated columns of droplets, which form a conducting bridge once a critical voltage (or electric field) has been reached. The strength of the electric field at which the sample shows a sharp increase in conductivity (increase in current through sample, between the two electrode plates) is recorded as the CEF. By this method, relative emulsion stability is compared quantitatively in terms of the CEF value and expressed in units of kV cm-1. In contrast to the method of Sjöblom, we have used alternating current with parallel-plate electrodes at the tip of a probe, which was submerged in the hydrocarbon medium. Comparison of crude-oil emulsions by CEF techniques is well-documented (Sullivan et al. 2004; Aske et al. 2002), but no reference to the use of CEF in chemical-demulsifier development could be found. It is the purpose of this study to develop the CEF technique for application in chemical-demulsifier research.

DC Electric Field-Enhanced Grain-Boundary Mobility in Magnesium Aluminate During Annealing

2016 ◽  
Vol 99 (6) ◽  
pp. 1951-1959 ◽  
Author(s):  
Jorgen F. Rufner ◽  
Derrick Kaseman ◽  
Ricardo H.R. Castro ◽  
Klaus van Benthem
Keyword(s):  
Grain Boundary ◽  
Electric Field ◽  
Magnesium Aluminate ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Dc Electric Field

Morphology of Σ3{/70.53°} grain boundaries in a C15 intermetallic compound

1994 ◽  
Vol 52 ◽  
pp. 684-685
Author(s):  
Fuming Chu ◽  
D. P. Pope ◽  
D. S. Zhou ◽  
T. E. Mitchell
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Crystallographic Analysis ◽  
Laves Phase ◽  
Second Phase ◽  
Bright Field Image ◽  
Boundary Edge ◽  
Arc Melting ◽  
Fcc Lattice ◽  
Diffraction Patterns

A C15 Laves phase, HfV2+Nb, shows promising mechanical properties and here we describe the structure of its grain boundaries. The C15 Laves phase has a fcc lattice with a=7.4Å. An alloy of composition Hf14V64Nb22 (including a C15 matrix and a second phase of V-rich bcc solution) was made by arc-melting. The alloy was homogenized at 1200°C for 120h. Preliminary study concentrated on Σ3{<110>/70.53°} grain boundaries in the C15 phase using Philips 400T and CM 30 microscopes.The most-commonly observed morphology of Σ3{<110>/70.53°} grain boundaries in the C15 phase is a faceted boundary. A bright field image (BFI) of the faceted boundary and the corresponding diffraction patterns with the grain boundary edge-on are shown in Fig. 1(a). From the diffraction patterns using a <110> zone axis for both grains, it is obvious that this is a Σ3{<110>/70.53°} grain boundary. Crystallographic analysis shows that the Σ3{<110>/70.53°} grain boundaries selectively facet with the following relationships between the two grains: {111}1//{111}2, {112}1//{112}2, {111}1//{115}2, and {001}1//{221}2.

Nonlinear photoacoustic effect of semiconductors in dc electric field

1990 ◽  
Vol 68 (8) ◽  
pp. 3865-3871 ◽  
Author(s):  
Jian‐chun Cheng ◽  
Shu‐yi Zhang ◽  
Yue‐sheng Lu
Keyword(s):  
Electric Field ◽  
Photoacoustic Effect ◽  
Dc Electric Field

Electric-Field Effects on Reactions Between Oxides

1997 ◽  
Vol 481 ◽  
Author(s):  
Matthew T. Johnson ◽  
Shelley R. Gilliss ◽  
C. Barry Carter
Keyword(s):  
Solid State ◽  
Electric Field ◽  
Elevated Temperatures ◽  
Ionic Current ◽  
Reaction Rates ◽  
Solid State Reactions ◽  
Interfacial Stability ◽  
Electric Field Effects ◽  
Thin Film Diffusion ◽  
Microscopy Techniques

ABSTRACTThin films of In2O3 and Fe2O3 have been deposited on (001) MgO using pulsed-laser deposition (PLD). These thin-film diffusion couples were then reacted in an applied electric field at elevated temperatures. In this type of solid-state reaction, both the reaction rate and the interfacial stability are affected by the transport properties of the reacting ions. The electric field provides a very large external driving force that influences the diffusion of the cations in the constitutive layers. This induced ionic current causes changes in the reaction rates, interfacial stability and distribution of the phases. Through the use of electron microscopy techniques the reaction kinetics and interface morphology have been investigated in these spinel-forming systems, to gain a better understanding of the influence of an electric field on solid-state reactions.

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