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Homework Help: Finding the concentrations of vacancies and interstitials

  1. Dec 12, 2016 #1
    Consider a two-dimensional ionic crystal with a primitive hexagonal lattice. The energy needed to create a Frenkel defect pair is 10eV, and Schottky defect formation costs 8eV.
    Calculate the concentration of vacancies and interstitials in the crystal at 300 K, assuming that all defects are intrinsic.

    Where: n = number of defects
    N = number of atoms in the crystal
    Edef = defect creation energy
    kb = Boltzman's constant
    T = temperature

    I've tried using 10eV and 8eV as the defect creation energy however this equals to an answer smaller than *10-100, unsure how to progress.

    Thanks in advance!
  2. jcsd
  3. Dec 14, 2016 #2


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    Staff: Mentor

    That is correct. The equilibrium concentration for those defects at room temperature is effectively zero.

    Why do we still have those defects in crystals?
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