LOGO Computational prediction on the interface structure of SiC(SiO 2 )-Cu(Cu 2 O) composites from first principles Adviser: Ray Zhang.

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LOGO

Computational prediction on the interface structure of

SiC(SiO2)-Cu(Cu2O) composites from first principles

Adviser: Ray Zhang （ professor ）Graduate student: Ruiyu Liu


LOGO1.1 Properties of SiC/Cu composites

Enhanced mechanical

Thermal Electrical properties

The wetting and bonding between SiC and Cu was the most concern in the preparation of SiC/Cu composites.


LOGO1.2 Reason of using computer simulations

It is very poor of wettability between copper and SiC. (R. Warren)

To address these issues, it is important to achieve an understanding of the atomic structure at the SiC/Cu interface.

1. Which interface is the favorite one?

2. Which factors should be weakened, and which factors should be enhanced?


LOGO2.1 Previous work

In the SiC/Cu coating particles, the surface of the SiC particles is covered by a film of SiO2 because of the oxidation in air.

SiC(100)-SiO2 interface


LOGO2.1 Previous work

The surface of Cu crystallites are also covered by Cu2O, formed because of the oxidation of copper crystallites by the dissolved air in the aqueous solution during the coating process Cu (001)-Cu2O(001) interface


LOGO2.2 SiC(100)-SiO2 interface model generation

1. The SiC(100) substrate modeled constraints a periodic 3×4 repeat unit.

2. Classical molecular dynamics were used to determine oxide structures which satisfy the imposed structural constraints, namely those deriving from the SiC substrate and from the periodic boundary conditions according to F. Devynck et al .

3. First principles calculations based on density functional theory (DFT) at level of the generalized gradient approximation were carried out.


LOGO2.3 Cu(100)-Cu2O interface model generation

Cu2O forms epitaxially with respect to the copper substrate where the relative orientation is (001) copper// (001) CuO2 and [001] copper//CuO2 and grows three-dimensionally to form oxide island according to our previous work.

The interface of Cu （ 001 ） /Cu2O （ 001 ） was built using Material Studio (MS).


LOGO2.4 Computational details

Five interface structure models between SiC(SiO2)-Cu(Cu2O) without any coordination defects were generated:

interface of SiC-Cu, interface of SiC(SiO2)-Cu, interface of SiC-Cu(Cu2O), interface of SiC(SiO2)-Cu(Cu2O) (weak model) interface of SiC(SiO2)-Cu(Cu2O) (strong model).



First principles calculations were carried out by CASTEP, which employs the density functional theory plane-wave pseudopotential method.

The generalized gradient approximation Predew-Wang (PW91) exchange-correlation functional was employed .

The kinetic cutoff for the plane-wave expansion was set to 400 eV, and Monkhorst-Pack k-point mesh was set to 3×4×1.



SiC-Cu interface SiC(SiO2)-Cu interface



SiC-Cu(Cu2O) interface SiC(SiO2)-Cu(Cu2O) interface (weak model)



SiC(SiO2)-Cu(Cu2O) interface (strong model)

The Cu2O layer is attached to the substrate through oxygen atoms bound to Cu atoms of the oxide film and to one Si atoms of the support.



The table showed that the spacing between the adjacent slabs In the interface of SiC(SiO2)-Cu(Cu2O):

Interface SiC-Cu SiC(SiO2)-Cu

Initial stage 3.5Å 3.5Å

Final stage 3.2Å 3.2Å

Interface SiC-Cu(Cu2O) SiC(SiO2)-Cu(Cu2O) (weak model)

Initial stage 3.6Å 3.9Å

Final stage 2.9Å 2.8Å


LOGO 3.1 Total energy of each material

Binding energy of interface ( ) is equal to the energy of breaking interface bond and dividing one interface into tow free surfaces.

abW


LOGO3.2 Total energy of each material

Materials SiC Cu

Total energy -0.635224710 E+003 eV

-5.39861652 E+00410eV

Materials SiC(SiO2) Cu(Cu2O)

Total energy -1.47015492 E+004

-7.45673703 E+004

Materials SiC-Cu SiC(SiO2)-Cu

Total energy -6.01525935

E+004

-6.83193004E+004

Materials SiC-Cu(Cu2O)

SiC(SiO2)-Cu(Cu2O) (weak model)

Total energy -7.26346895

E+004

Materials SiC(SiO2)-Cu(Cu2O) (strong model)

Total energy


LOGO3.3 Binding energy of the five interface

Interface SiC(SiO2) Cu(Cu2O)

Binding energy

Interface SiC-Cu SiC(SiO2)-Cu

Binding energy

Interface SiC-Cu(Cu2O)

Binding energy -576.9761 ev

Interface SiC(SiO2)-Cu(Cu2O) (weak model)

Binding energy

Interface SiC(SiO2)-Cu(Cu2O) (strong model)

Binding energy


LOGO4. Unfinished conclusion

1. Binding energy

Know which interface is the favorite one?

2. Density of State

Know why through analyzing bonding properties.


LOGO

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LOGO Computational prediction on the interface structure of SiC(SiO 2 )-Cu(Cu 2 O) composites from first principles Adviser: Ray Zhang.

Documents

interface of cu

cu interface slide

cu interface sicsio

o interface sicsio

siccu interface

o001 interface slide

interface structure

o interface weak model