Data
Character table：
| TiB2 | ZrB2 | TaB2 | NbB2 | WB | MoB | CrB | LaB6 | |
|---|---|---|---|---|---|---|---|---|
| Boron content[%] | 31.11 | 19.16 | 10.67 | 18.88 | 5.55 | 10.13 | 17.21 | 31.83 |
| Crystal structure | Hexagonal | Hexagonal | Hexagonal | Hexagonal | Tetragonal | Tetragonal | Orthorhombic | Cubic |
| Lattice periods,kx. a | 3.026 | 3.168 | 3.078 | 3.089 | 3.115 | 3.110 | 2.969 | 4.1561 |
| b or c | 3.213 | 3.528 | 3.265 | 3.303 | 16.93 | 16.97 | b 7.858 C 3.002 | |
| c/a | 1.062 | 1.114 | 1.050 | 1.060 | 5.42 | 5.45 | ||
| Density[g/cm3] calculated |
4.530 | 6.09 | 12.62 | 7.00 | 15.734 | 8.665 | 6.11 | 4.722 |
| experimental | 4.38 | 6.17 | 12.38 | 6.97 | ～15.4 | 8.3 | 6.05 | 4.76 |
| Microhardness 30g [kg/mm2] |
3370±60 | 2252±22 | 2500±42 | 2600 | 3700(50g) | 2350(50g) | ～1300(100g) | 2770±60 |
| Melting Point[℃] | 2790 | 3200 | 3037 | 3000 | 2800 | 2550 | 2100 | 2530 |
| Heat of formation ΔH°(298）[Kcal/mol] |
-70.0 | -76.7 | -46 | -59 | -17 | -16.3 | (CrB2) -30 | -112.3 |
| Entropy S°(298) [Kcal/mol・℃] |
7.52 | 10.7 | 13.9 | 10.4 | 5.8 | |||
| Specific electrical resistance[μΩ・cm] at 20℃ |
9.0 | 9.7 | 32.5 | 25.7 | ～22 | 45 | 45.5 | 15.0 |
| Point of transition to superconductivity °K |
<1.28 | <1.80 | <1.28 | <1.0 | <1.28 | <1.28 | <1.28 | 5.7 |
(Reference) Hand book refractory compounds (metallurgiya in Moscow 1976 editions)
