1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Heat capacity of diamond

  1. Mar 24, 2009 #1
    http://www.ph.ed.ac.uk/~pmonthou/Statistical-Mechanics/documents/SM9.pdf [Broken]

    In the third last paragraph of p36, we are told that the Einstein model discussed in this lecture succesfully explains the low heat capacity of diamond - i can't however see how it does, or at least find an explanation anywhere in that lecture.

    I follw the argument that at low T, x is large and so the thermal energy is small in comparison to the energy difference between the ground state and the first excited state but how does that help explain the low heat capacity of diamond - surely all we can gather from this is that it's going to be statistically more likely to find particles in the diamond lattice in the ground state???
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 24, 2009 #2

    Mapes

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Re: Diamonds

    For diamond, [itex]\kappa[/itex] is relatively large (p34), so [itex]\omega[/itex] is large, so [itex]T^*[/itex] is large, so [itex]T/T^*[/itex] is small, so [itex]c_v[/itex] is small.
     
  4. Mar 24, 2009 #3
    Re: Diamonds

    what's the relationship between [itex]\omega[/itex] and T*?

    and how did u conclude that [itex]C_v[/itex] was going to be small as a result of that ratio being small?
     
  5. Mar 24, 2009 #4

    Mapes

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Re: Diamonds

    From the bottom of p35, [itex]T^*\propto \omega[/itex]; from the graph on the bottom right of p36, [itex]c_v[/itex] decreases with increasing [itex]T^*[/itex].
     
  6. Mar 24, 2009 #5
    Re: Diamonds

    You have to look at the properties of diamond. It's SP3 hybrid bond, thus it make a non-polar molecule. We can see that it has no free electron moving inside the lattice and by calculate the total energy inside the 3 dimensional crystal with it's own Madelug constant, we found it's a good heat conductance and good isolator (bandgap 5.5 at 300K). No free electron no electron collision, tightly bond so less translation, the contribute more to vibrational.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Heat capacity of diamond
Loading...