Can a strained diamond actually become conductive?

Question

According to about.com,

"The electrical resistivity of most diamonds is on the order of 10¹¹ to 10¹⁸ Ω·m" (source)

However, according to the diamond band diagram, it seems that under a certain range of tensile strain, a diamond becomes conductive, since its band gap vanishes:

(source)

Is it actually possible to achieve this situation?

Answer 1

The maximum you can strain silicon, for example, before crystalline defects are introduced is ~1%, at which point the conductivity would go down. In the diamond case, the diagram indicates that you’d have to strain it by 200% (i.e. the atoms would have to be spaced twice as far apart as their equilibrium distance) to have no bandgap. This would be far too energetically unfavourable to happen. The material would break apart or be extremely defective well before this amount of strain is reached.

In other words (@JohnRennie), since this is a calculated band structure, there is no way to achieve this effect in diamond because it would fracture long before the C-C distance became large enough to merge the bands

Carbon can be very conductive (some forms of carbon nanotubes for example are metallic), but carbon in these forms is definitely not diamond.