Debye temperature

Definition

The Debye temperature is a characteristic temperature that indicates the temperature below which the specific heat capacity of a solid approaches zero. It is derived from the Debye model, which describes the phonon contribution to the specific heat in a solid.

5 Must Know Facts For Your Next Test

1. The Debye temperature is denoted by $\theta_D$ and is typically measured in Kelvin.
2. It represents the highest temperature at which quantum effects are significant for lattice vibrations or phonons in a solid.
3. At temperatures much lower than $\theta_D$, the specific heat capacity of a solid increases as $T^3$, according to the Debye T^3 law.
4. As temperature approaches $\theta_D$, the specific heat capacity converges to a constant value, similar to that predicted by classical Dulong-Petit law.
5. $\theta_D$ can be experimentally determined using techniques such as specific heat measurements or neutron scattering.

Review Questions

• What does the Debye temperature indicate about a solid's thermal properties?
• How does specific heat behavior change as temperature moves below and above $\theta_D$?
• What methods can be used to experimentally determine the Debye temperature?

Related terms

Phonon: A quantized mode of vibration occurring in a rigid crystal lattice, contributing to thermal conductivity and specific heat.

Specific Heat Capacity: The amount of heat required to change a substance's temperature by one degree per unit mass.

Dulong-Petit Law: $C_V \approx 3R$ for many solid crystalline elements at high temperatures, where $C_V$ is molar specific heat at constant volume and $R$ is the gas constant.