The description of phonon heat conduction has typically been based on Fourier diffusion theory. However, over the past three decades, a host of interesting phonon transport phenomena beyond the Fourier diffusion picture have drawn much attention. Although most of the studies focused on classical size effects that lead to reduced thermal conductivity, other phenomena have been observed, often at the microscale and nanoscale, that are either completely novel or appear only at elevated temperatures. Examples are the prediction and observation of phonon second sound at high temperatures, quantized heat conduction and Anderson localization. These developments reveal rich phonon heat conduction phenomena analogous to those of electrical conduction. This Review discusses different non-Fourier heat conduction regimes (including the Casimir–Knudsen classical size effect regime), phonon hydrodynamics, the coherent phonon transport regimes (including localization and quantization of heat conduction) and the possibility of divergent heat conduction in low dimensions.

声子热传导的描述通常基于傅立叶扩散理论。然而，在过去的三十年里，傅立叶扩散图之外的许多有趣的声子传输现象引起了很多关注。尽管大多数研究都集中在导致热导率降低的经典尺寸效应上，但也观察到了其他现象，通常在微米级和纳米级，这些现象要么是全新的，要么仅在升高的温度下出现。例子是高温下声子第二声的预测和观察、量化热传导和安德森定位。这些发展揭示了类似于电传导的丰富的声子热传导现象。