Debye Model

In thermodynamics and solid state physics, the Debye model is a method of calculating the phonon contribution to the specific heat in a solid. It improves upon the Einstein model, which assumes a single phonon frequency, by approximating the phonon density of states as a constant up to a cutoff frequency, called the Debye frequency. This model correctly predicts the low temperature dependence of the heat capacity, which is proportional to T3, and it also recovers the Dulong-Petit law at high temperatures. According to the Debye model, which was developed by Peter Debye in 1913, C_V(T)=\begin{cases} \frac{12}{5}\pi^4k_BN(\frac{T}{\theta_D})^3, & \mbox{if }T<<\theta_D \\ 3Nk_B, & \mbox{if }T>>\theta_D \end{cases} where \theta_D is the Debye temperature, which is characteristic for each material. The following table lists Debye temperatures for several metals:
\theta_D(K)
Aluminum 426
Cadmium 186
Chromium 610
Copper 344.5
Gold 165
\alpha-Iron 464
Lead 96
\alpha-Manganese 476
Nickel 440
Platinum 240
Silicon 640
Silver 225
Tin (white) 195
Titanium 420
Tungsten 405
Zinc 300
Diamond 2200
Ice 192

References

CRC Handbook of Chemistry and Physics, 56th Edition (1975-1976)

 

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