Table 2 Calculated defect formation energies in U3Si2 and SiC.

From: Understanding the interface interaction between U3Si2 fuel and SiC cladding

 

Three-phase equilibria

Point defect in U3Si2

U3Si2-SiC-U3Si5

U3Si2-SiC-UC

U3Si2-SiC-USi

U3Si2-SiC-U20Si16C3

U3Si2-U3Si5-U20Si16C3*

U3Si2-U3Si5-UC*

U1 vac.

0.87

0.41

1.10

−10.27

0.87

0.87

U2 vac.

2.22

1.76

2.44

−8.93

2.22

2.22

Si vac.

1.13

1.82

0.79

17.84

1.13

1.13

U-on-Si

0.66

1.81

0.10

28.52

0.66

0.66

Si-on-U1

0.40

−0.75

0.97

−27.45

0.40

0.40

Si-on-U2

1.67

0.52

2.23

−26.19

1.67

1.67

Si in site 2b

−0.24

−0.93

0.10

−16.95

−0.24

−0.24

Si in site 4h

1.63

0.94

1.97

−15.09

1.63

1.63

C-on-U1

1.29

1.52

1.18

6.86

3.15

2.44

C-on-U2

2.27

2.50

2.15

7.84

4.12

3.42

C-on-Si

1.27

2.65

0.59

34.70

3.12

2.42

C in site 2b

−1.29

−0.60

−1.63

15.42

0.56

−0.14

C in site 4g

0.06

0.75

−0.28

16.78

1.92

1.21

C in site 4h

−0.24

0.45

−0.58

16.48

1.62

0.91

C in site 8i

6.42

7.11

6.08

23.14

8.28

7.57

Point defect in SiC

U3Si2-SiC-U3Si5

U3Si2-SiC-UC

U3Si2-SiC-USi

U3Si2-SiC-U20Si16C3

SiC-UC-U20Si16C3*

SiC-U3Si5-UC*

Si vac.

7.25

7.95

6.92

23.97

7.78

7.69

C vac.

4.82

4.13

5.16

−11.89

4.30

4.39

Si vac. in Si-on-C**

−0.05

0.64

−0.39

16.67

0.48

0.38

U-on-Si

4.34

5.49

3.78

32.20

5.49

5.49

U-on-C

11.18

10.95

11.29

5.61

11.27

11.47

Si-on-C

4.87

3.49

5.55

−28.56

3.81

4.01

C-on-Si

2.48

3.86

1.81

35.91

3.54

3.35

U in site 4b

12.88

13.34

12.66

24.03

13.50

13.60

U in site 4d

14.61

15.07

14.39

25.76

15.23

15.33

  1. Defect formation energies (\(\Delta E_{\mathrm{f}}^D\)) in eV/defect atom, in U3Si2 at chemical potentials governed by the indicated three-phase equilibria. Negative \(\Delta E_{\mathrm{f}}^D\) values are shown bold.
  2. *Fuel and cladding not in contact.
  3. **Si-on-C anti-site with vacancy on Si anti-site.
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