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Vibrational Entropy

  1. Sep 16, 2009 #1
    Hello all,

    I am looking at the entropy of mixing for a binary AxB1-x alloy and I was wondering, when is it a valid assumption to neglect the contribution arising from the change in vibrational entropy between the mixed and the unmixed state.

    Thanks in advance!!
  2. jcsd
  3. Sep 16, 2009 #2
    Does the crystal structure change? How large is x? For small x it is probably reasonable, but might not be if A and B are very different atomic weights.
  4. Sep 16, 2009 #3

    As an example, consider GaN-GaP pseudobinary system in the wurtzite phase. In pure GaN, GaP both N and P atoms are terahedrally coordinated to Ga. In a mixed state, these atoms have the same local chemical environment. In that case would it be a valid assumption to neglect the change in vibrational entropy?
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