Limiting factors in Diamond Anvil Cells

[g_mogni]

Hello, I'm trying to better understand the limiting factors in Diamond Anvil Cells that limit the achievable pressure to around 7 or 8 Mbar at the moment, despite not being a specialist. For example, is there a special reason other than the tiny size of the crystal sample used in DACs for why the sample has to be squeezed between diamond tips which easily fracture, and not say relatively large smooth diamond parallel plates which I think would be more resistant to fracture?

Thanks,

Gabriele

 

[Rajini]

Hello,
I don't know much about the instrumentation details of the diamond cell setup. But the answer could be pressure is defined as force per unit area. So by just applying a relatively little pressure on the edges of the diamonds, can get a maximum pressure on the sample (small sample=more pressure!).
Cheers, Raj

 

[g_mogni]

Thanks for the answer. My supposition is that if we could get a larger sample to be compressed at the same pressure by applying a larger force, then we could apply the compression with parallel flat diamond plates rather than diamond tips which I believe fracture much more easily than the plates... please have a look at the attached figure for a visual explanation...

G

 

[anorlunda]

Thanks for the answer. My supposition is that if we could get a larger sample to be compressed at the same pressure by applying a larger force, then we could apply the compression with parallel flat diamond plates rather than diamond tips which I believe fracture much more easily than the plates... please have a look at the attached figure for a visual explanation...

G

Your supposition sounds correct. But @Ra@wr alias also correct about additional force. If the flag surface has 1000x area of a pointed tip, you will need 1000x more force.

It would be reasonable to assume that designers of existing diamond anvils considered the tradeoff between lifetime and cost. perhaps you could find one of them to discuss it with.