- #1
Arran
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Homework Statement
Consider a crystal of copper with the f.c.c. structure. Suppose the energy costs for creating a one-atom vacancy in the material is 1.1eV. The melting temperature of the material is 1356K. Estimate equilibrium density of vacancies in the material.
Homework Equations
NV/NL=exp(-Δhf/kT)
where NV is the number of vacancies,
NL is the number of lattice sites,
Δhf is the energy required to create a one-atom vacancy,
& k is boltzmann's constant
The Attempt at a Solution
Equilibrium density of vacancies = NV/NL=exp(-Δhf/kT)=
=exp(-1.1*1.6*10-19/1.38*10-23*300)=3.45*10-19
I think I understand the equation and am able to derive it. However, I don't understand the relevance of the melting temperature. I assume the "equilibrium" implies room temperature, so I use T=300K. Also I don't see the relevance of the crystal structure, f.c.c.
Please help me. I feel as though I am missing the point of the equation :)