Material Data：Transition Metal Carbide Cathodes
| Parameter | Units | HfC | ZrC | NbC | TaC | TiC | VC |
|---|---|---|---|---|---|---|---|
| Molecular Weight | g/mol | 190.51 | 103.23 | 104.92 | 192.96 | 59.91 | |
| Stoichiometry | N/A | ~1 | ~1 | ~1 | ~1 | ~1 | ~1 |
| Metal Impurities | ppm by wt. | <30 | <30 | <30 | <30 | <30 | <30 |
| Lattice Parameter | Angstroms | 4.64 | 4.7 | 4.468 | 4.454 | 4.328 | 4.16 |
| Melting Temperature | K | ~4160 | ~3300 | ~3770 | ~4150 | ~3430 | |
| Density | g/cm3 | 12.2 | 6.59 | 7.79 | 14.5 | ||
| Hardness | Kg/mm2 | 2600 | 2470 | 1800 | 3200 | ||
| Coefficient of Thermal Expansion @ 300-3000 K | α × 10^6 | 7.3 ± 0.2 | 7.6 ± 0.2 | 9.5 ± 0.3 | |||
| Thermal Conductivity | cal-cm/(s-cm2-C) | 0.049 | 0.034 | 0.053 | 0.049 | ||
| Electrical Resistivity | µΩ-cm | 109 | ~70 | 74 | 170-200 | 180-250 | |
| Effective Work Function (100) at 1800 K | eV | 3.58 | 3.53 | 4.00 | 4.20 | 3.80 | |
| Absolute Work Function (100) at 300 K | eV | 3.5 | 4.12 | ||||
| Spectral Emissivity (@ 0.65 microns & 2000 K) | N/A | 0.645 | 0.48 | 0.359 | 0.365 | 0.487 | 0.433 |
| Evaporation rate at 1800 K (UHV) | g/cm2/s | <10^-9 | <10^-9 | ||||
| Orientation limit for specific orientation | degrees | <2 | <2 | <2 | <2 | <2 | <2 |
