Ab Initio Study of Electronic Transport in Cubic-HfO2 Grain Boundaries

In polycrystalline materials the grain boundaries (GBs) are particularly important as they can act as a sink for atom defects and impurities, which may drive structural transformation of the materials and consequently modify their properties. Characterising the structure and properties of GBs is critical for understanding and controlling material property. Here, we investigated how GBs can modify the structural, electronic, and transport properties of the polycrystalline material HfO2. In general, grain boundaries are considered to be detrimental to the physical stability and electronic transport in HfO2. Anyway, studying by first principles the two most stable and common types of GBs, the tilt and the twist, we found substantial differences on the impact they have on the material properties. In fact, while tilt defects create channels of different sizes and shapes in hafnia along which the electronic transport is stronger in relation to leakage current through GBs, twist defects create a sort of amorphous structure that tends to resemble the bulk and which is independent of the number of rotated planes/atoms.

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The Brittle Fracture of Polycrystalline Zinc

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.348-349.41 ◽

2007 ◽

Vol 348-349 ◽

pp. 41-44 ◽

Cited By ~ 1

Author(s):

Gareth M. Hughes ◽

Gillian E. Smith ◽

Peter E.J. Flewitt ◽

A.G. Crocker

Keyword(s):

Brittle Fracture ◽

Grain Boundaries ◽

Polycrystalline Material ◽

Ion Beam ◽

Geometric Modelling ◽

Polycrystalline Materials ◽

Experimental Measurements ◽

Small Punch ◽

Polycrystalline Zinc ◽

Focussed Ion Beam

In polycrystalline materials grain boundaries provide an important contribution to the resistance to the propagation of both brittle and ductile cracks. In this paper we describe experimental measurements of brittle cracks developed within both small punch and matchstick test specimens of polycrystalline hcp zinc. These specimens were tested over the temperature range 77 to 423K. Fractography undertaken using focussed ion beam imaging provides detail of the propagation from grain to grain and across {10-12} twins of (0001) basal and {10-10} prismatic cleavage cracks. The results are discussed by comparison with the predictions from previously described 3-D geometric modelling applied to this hcp polycrystalline material.

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Analyzing the Impact of Grain Boundary Scattering on the Metal Resistivity: First-Principles Study of Symmetric Tilt Grain Boundaries in Copper

Springer Proceedings in Physics - The Physics of Semiconductor Devices ◽

10.1007/978-3-319-97604-4_107 ◽

2019 ◽

pp. 691-695

Author(s):

Hemant Dixit ◽

Aniruddha Konar ◽

Rajan Pandey ◽

Jin Cho ◽

Francis Benistant

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

First Principles ◽

Boundary Scattering ◽

First Principles Study ◽

Grain Boundary Scattering ◽

Symmetric Tilt ◽

The Impact

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Effect of Grain Boundary Ledges on the Flow Stress in Nickel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078948 ◽

1977 ◽

Vol 35 ◽

pp. 284-285

Author(s):

Eswarahalli S. Venkatesh ◽

L.E. Murr

Keyword(s):

Flow Stress ◽

Grain Boundary ◽

Grain Boundaries ◽

Polycrystalline Materials ◽

Structure And Properties ◽

Boundary Dislocation ◽

Dislocation Source ◽

Type Relation ◽

Ledge Density ◽

Boundary Ledge

In a recent paper1 it was shown that grain boundary ledge structure can be changed by appropriate thermomechanical treatments. Grain boundary ledges are sources of dislocations2. Recently the effects of grain boundaries on the mechanical properties in metals and alloys were studied3,4. For a few years now the structure and properties of grain boundaries and their control have been considered as a means of strengthening polycrystalline materials5,6. Li5 has derived a Hall-Petch type relation in terms of grain boundary dislocation source (ledge) density, m, in the form where L is the grain size, σ0 and α are constants, and G ana b have the usual meaning. The influence of grain boundary ledge density, on the flow stress is considered in this paper.In the present work, pure (99.98%) nickel sheet mill rolled (hot) to 0.022 in. thick was used.

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Observation of secondary slip systems in tungsten bicrystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100112361 ◽

1984 ◽

Vol 42 ◽

pp. 478-479

Author(s):

J. R. Fekete ◽

R. Gibala

Keyword(s):

Stress Field ◽

Grain Boundaries ◽

Deformation Behavior ◽

Stress Axis ◽

Polycrystalline Materials ◽

Slip Systems ◽

Metallic Materials ◽

Twist Boundary ◽

Secondary Slip ◽

Plane Normal

The deformation behavior of metallic materials is modified by the presence of grain boundaries. When polycrystalline materials are deformed, additional stresses over and above those externally imposed on the material are induced. These stresses result from the constraint of the grain boundaries on the deformation of incompatible grains. This incompatibility can be elastic or plastic in nature. One of the mechanisms by which these stresses can be relieved is the activation of secondary slip systems. Secondary slip systems have been shown to relieve elastic and plastic compatibility stresses. The deformation of tungsten bicrystals is interesting, due to the elastic isotropy of the material, which implies that the entire compatibility stress field will exist due to plastic incompatibility. The work described here shows TEM observations of the activation of secondary slip in tungsten bicrystals with a [110] twist boundary oriented with the plane normal parallel to the stress axis.

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Morphology and atomic structure of segregated grain boundaries in Cu-Sb

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121673 ◽

1992 ◽

Vol 50 (1) ◽

pp. 254-255

Author(s):

R. W. Fonda ◽

D. E. Luzzi

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Intergranular Fracture ◽

Atomic Structure ◽

Copper Alloys ◽

Polycrystalline Materials ◽

Grain Boundary Embrittlement ◽

Boundary Embrittlement

The properties of polycrystalline materials are strongly dependant upon the strength of internal boundaries. Segregation of solute to the grain boundaries can adversely affect this strength. In copper alloys, segregation of either bismuth or antimony to the grain boundary will embrittle the alloy by facilitating intergranular fracture. Very small quantities of bismuth in copper have long been known to cause severe grain boundary embrittlement of the alloy. The effect of antimony is much less pronounced and is observed primarily at lower temperatures. Even though moderate amounts of antimony are fully soluble in copper, concentrations down to 0.14% can cause grain boundary embrittlement.

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The effect of ionic defect interactions on the hydration of yttrium-doped barium zirconate

Physical Chemistry Chemical Physics ◽

10.1039/d0cp06587k ◽

2021 ◽

Author(s):

Sebastian Eisele ◽

Fabian M. Draber ◽

Steffen Grieshammer

Keyword(s):

Monte Carlo ◽

Monte Carlo Simulations ◽

First Principles ◽

Barium Zirconate ◽

First Principles Calculations ◽

Defect Interactions ◽

The Impact ◽

Ionic Defect

First principles calculations and Monte Carlo simulations reveal the impact of defect interactions on the hydration of barium-zirconate.

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Insight into the Impact of Zr/Ti Ratios on the Structure and Properties of PLZST Antiferroelectric Thick Films

physica status solidi (a) ◽

10.1002/pssa.202000579 ◽

2021 ◽

Author(s):

Yucheng Liu ◽

Shaopeng Liu ◽

Tongqing Yang

Keyword(s):

Thick Films ◽

Structure And Properties ◽

Antiferroelectric Thick Films ◽

The Impact ◽

Insight Into

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Influence of Whey Protein Micro-Gel Particles and Whey Protein Micro-Gel Particles-Xanthan Gum Complexes on the Stability of O/W Emulsions

Polymers ◽

10.3390/polym13142301 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2301

Author(s):

Man Zhang ◽

Bin Liang ◽

Hongjun He ◽

Changjian Ji ◽

Tingting Cui ◽

...

Keyword(s):

Oxidative Stability ◽

Whey Protein ◽

High Speed ◽

Xanthan Gum ◽

Physical Stability ◽

Theoretical Support ◽

Gel Particles ◽

Oil In Water ◽

The Stability ◽

The Impact

Appropriate pretreatment of proteins and addition of xanthan gum (XG) has the potential to improve the stability of oil-in-water (O/W) emulsions. However, the factors that regulate the enhancement and the mechanism are still not clear, which restricts the realization of improving the emulsion stability by directional design of its structure. Therefore, the effects of whey protein micro-gel particles (WPMPs) and WPMPs-XG complexes on the stability of O/W emulsion were investigated in this article to provide theoretical support. WPMPs with different structures were prepared by pretreatment (controlled high-speed shear treatment of heat-set WPC gels) at pH 3.5–8.5. The impact of initial WPC structure and XG addition on Turbiscan Indexes, mean droplet size and the peroxide values of O/W emulsions was investigated. The results indicate that WPMPs and XG can respectively inhibit droplet coalescence and gravitational separation to improve the physical stability of WPC-stabilized O/W emulsions. The pretreatment significantly enhanced the oxidative stability of WPC-stabilized O/W emulsions. The addition of XG did not necessarily enhance the oxidative stability of O/W emulsions. Whether the oxidative stability of the O/W emulsion with XG is increased or decreased depends on the interface structure of the protein-XG complex. This study has significant implications for the development of novel structures containing lipid phases that are susceptible to oxidation.

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