x content | Density (g/cm3) | Average grain size (mm) | e | kp | kt | −d31 (pC/N) |
0 | 4.03 ± 0.01 | 0.4 ± 0.15 | 470 | 0.12 | 0.29 | 15 |
2 | 4.15 ± 0.01 | 0.8 ± 0.1 | 577 | 0.16 | 0.36 | 23 |
4 | 4.26 ± 0.02 | 1.7 ± 0.3 | 744 | 0.27 | 0.40 | 41 |
6 | 4.16 ± 0.01 | 2.0 ± 0.2 | 650 | 0.17 | 0.28 | 20 |