The effect of segregation structure on the colossal permittivity properties of (La0.5Nb0.5)xTi1−xO2 ceramics

2018 ◽  
Vol 6 (9) ◽  
pp. 2283-2294 ◽  
Author(s):  
Lingxia Li ◽  
Te Lu ◽  
Ning Zhang ◽  
Jiangteng Li ◽  
Zhaoyang Cai
Keyword(s):  
Grain Boundary ◽  
Activation Energies ◽  
Colossal Permittivity ◽  
Segregation Structure

The activation energies of the grain-boundary and different polarizations are researched to reveal the effect of the segregation structure on the performance.

Control of grain boundary in alumina doped CCTO showing colossal permittivity by core-shell approach

2018 ◽  
Vol 38 (9) ◽  
pp. 3182-3187 ◽  
Author(s):  
Sonia De Almeida-Didry ◽  
Meledje Martin Nomel ◽  
Cécile Autret ◽  
Christophe Honstettre ◽  
Anthony Lucas ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Core Shell ◽  
Colossal Permittivity

scholarly journals Comparison of colossal permittivity of CaCu3Ti4O12 with commercial grain boundary barrier layer capacitor

2019 ◽  
Vol 96 ◽  
pp. 105943
Author(s):  
Sonia De Almeida-Didry ◽  
Cécile Autret ◽  
Anthony Lucas ◽  
François Pacreau ◽  
François Gervais
Keyword(s):  
Grain Boundary ◽  
Barrier Layer ◽  
Colossal Permittivity ◽  
Grain Boundary Barrier

Analysis of defect formation in Nb-doped SrTiO3 by impedance spectroscopy

2001 ◽  
Vol 16 (1) ◽  
pp. 192-196 ◽  
Author(s):  
Seong-Ho Kim ◽  
Jung-Ho Moon ◽  
Jae-Hwan Park ◽  
Jae-Gwan Park ◽  
Yoonho Kim
Keyword(s):  
Activation Energy ◽  
Impedance Spectroscopy ◽  
Grain Boundary ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Thermal Activation ◽  
Oxygen Vacancies ◽  
Defect Formation ◽  
Activation Energies ◽  
Single Grain

The thermal activation energies for conduction of Nb-doped SrTiO3 grains and grain boundaries have been investigated by impedance spectroscopy. First, to observe the effect of electrode/SrTiO3 bulk interface, the varied impedances of SrTiO3 single crystal were measured with temperatures. The activation energy of an electrode/bulk interface was determined to be 1.3 eV, whereas that of bulk was 0.8 eV. When the impedances of Nb-doped SrTiO3 ceramics were measured, it was suggested that the more precise impedance values of a single grain and a single grain to grain junction be obtained using a microelectrode method. The activation energies for a grain, a grain boundary, and an electrode/bulk interface were determined to be about 0.8, 1.3, and 1.5 eV, respectively. From these measured results, it was suggested that the activation energy, 0.8 eV, measured in grain was originated from oxygen vacancies and the activation energy, 1.3 eV, in grain boundary was from strontium vacancies.

Electromigration Characteristics of Cu and Al Interconnections

1994 ◽  
Vol 338 ◽  
Author(s):  
S. Shingubara ◽  
K. Fujiki ◽  
A. Sano ◽  
H. Sakaue ◽  
Y. Horiike
Keyword(s):  
Grain Boundary ◽  
Activation Energies ◽  
Dislocation Dynamics ◽  
Small Resistance ◽  
Non Local ◽  
Rapid Transport ◽  
The One

ABSTRACTElectromigration activation energies (Ea) of Al and Cu interconnections are strongly dependent on the grain boundary morphology, and it is pointed out that Ea of bamboo-like Al interconnection is not less than Ea of small grain Cu interconnections. Small resistance oscillatory changes caused by electromigration, which are classified into three categories; oscillation, downward spikes, and upward spikes, are investigated in detail. It seems most likely that oscillations correspond to annihilation and formation of the one void. It is also pointed out that downward spikes are local, while upward spikes are non-local. Dislocation dynamics such as generation, rapid transport and subsequent annihilation are considered to be origins of spikes.

scholarly journals Molecular Dynamics Simulation of High-Temperature Creep Behavior of Nickel Polycrystalline Nanopillars

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2606
Author(s):  
Xiang Xu ◽  
Peter Binkele ◽  
Wolfgang Verestek ◽  
Siegfried Schmauder
Keyword(s):  
Molecular Dynamics ◽  
High Temperature ◽  
Grain Boundary ◽  
Creep Behavior ◽  
Activation Energies ◽  
Dynamics Simulation ◽  
Dislocation Creep ◽  
Creep Process ◽  
High Temperature Creep ◽  
Temperature Creep

As Nickel (Ni) is the base of important Ni-based superalloys for high-temperature applications, it is important to determine the creep behavior of its nano-polycrystals. The nano-tensile properties and creep behavior of nickel polycrystalline nanopillars are investigated employing molecular dynamics simulations under different temperatures, stresses, and grain sizes. The mechanisms behind the creep behavior are analyzed in detail by calculating the stress exponents, grain boundary exponents, and activation energies. The novel results in this work are summarized in a deformation mechanism map and are in good agreement with Ashby’s experimental results for pure Ni. Through the deformation diagram, dislocation creep dominates the creep process when applying a high stress, while grain boundary sliding prevails at lower stress levels. These two mechanisms could also be coupled together for a low-stress but a high-temperature creep simulation. In this work, the dislocation creep is clearly observed and discussed in detail. Through analyzing the activation energies, vacancy diffusion begins to play an important role in enhancing the grain boundary creep in the creep process when the temperature is above 1000 K.

scholarly journals Peculiarities of charge carrier relaxation in grain boundary of gadolinium-doped ceria ceramics

2019 ◽  
Vol 59 (2) ◽  
Author(s):  
Saulius Kazlauskas ◽  
Edvardas Kazakevičius ◽  
Artûras Žalga ◽  
Saulius Daugėla ◽  
Algimantas Kežionis
Keyword(s):  
Grain Boundary ◽  
Electrical Response ◽  
Sol Gel ◽  
Relaxation Times ◽  
Activation Energies ◽  
Electrode Impedance ◽  
Doped Ceria ◽  
Electrical Measurements ◽  
Exponential Factor ◽  
Gadolinium Doped Ceria

Two different gadolinium-doped ceria ceramics are prepared from two different powders, one commercially available synthesised by solid state reaction and another produced by tartaric acid assisted sol–gel synthesis. The specimens have a different microstructure, while the XRD patterns of powders showed a pure cubic fluorite structure without any impurity phase. The electrical properties are studied at frequencies up to 10 GHz by combining broadband 2-electrode and 4-electrode impedance spectroscopy methods. Primary electrical measurements showed that the values of grain conductivity and its activation energies for both ceramics were nearly the same. However, due to different contributions of the grain boundary mediums, total conductivities and their activation energies are found to be considerably different. The advantage of the 4-electrode method allowed us to measure the pure electrical response of grain boundaries, bypassing any interferences caused by interfacial impedance. By using these data, the temperature behaviour of distribution of relaxation times in the grain boundary is studied. A broadening of this distribution with increasing temperature is found for both specimens, contrary to a previously observed phenomenon in the grain of oxygen ion conductive ceramics and single crystals. It is shown that, supposing individual relaxation times behave according to the Arrhenius law, both activation energy and pre-exponential factor must be distributed.

Oxygen Self-Diffusion In Mgo Grain Boundaries

1994 ◽  
Vol 357 ◽  
Author(s):  
Michael Liberatore ◽  
Bernhardt J. Wuensch
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Experimental Error ◽  
Boundary Diffusion ◽  
High Energy ◽  
Activation Energies ◽  
Grain Boundary Diffusion ◽  
Low Energy ◽  
Enhanced Diffusion ◽  
Self Diffusion

AbstractOxygen grain boundary diffusion has been studied in low energy (∑5, ∑13) and high energy (asymmetric 16° tilt) MgO grain boundaries. Enhanced diffusion of oxygen was observed in all boundaries, but more so in the general, high energy boundary, by 1 - 2 orders of magnitude. This supports the theory that the better the atomic registry between the adjoining grains the lower the diffusivities in the grain boundary. Also the activation energies for bulk and grain boundary diffusion (in the ∑13 boundaries) were found to be equal to within experimental error. (≈ 3.9eV)

Studying Motion of 〈100〉 Tilt Grain Boundaries Using Molecular Dynamics Simulation

2014 ◽  
Vol 1704 ◽  
Author(s):  
Shijing Lu ◽  
Donald W. Brenner
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Grain Boundary ◽  
Driving Force ◽  
Boundary Migration ◽  
Activation Energies ◽  
Dynamics Simulation ◽  
Grain Boundary Migration ◽  
Boundary Velocity ◽  
Rate Limiting

ABSTRACTIn the study of grain boundary migration of metallic materials using molecular dynamics simulation (MDS), grain boundary mobilities and activation energies are often found to be different from experimentally observed values. To reconcile the discrepancies, tremendous effort has been made to replicate experiment conditions in MDS, e.g.as low a driving force as possible, near zero grain boundary velocity. In the present study, we propose an analytic method that removes effects from non-physical conditions such as high driving force or high temperature. The analytic model presumes that two types of rate limiting events coexist during grain boundary migration. Kinetics parameters, such as activation energies, of the rare events are different and therefore should be modeled separately. Activation energies from this model are closer to experiment than previously reported values. Further, by analyzing the evolution of atomic structures, these two types of rate limiting events correspond to shear coupled migration and grain boundary sliding mechanisms, respectively.

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