陈晓嘉教授团队Nature Reviews Physics：极端压力下原位测量热导率

材料的热导率对于许多实际应用非常重要，例如，了解地球的热平衡和历史、器件的能量转换以及电子设备的热管理。然而，在压力条件下，测量材料的热导率和理解相关的热传输机制，仍然是高压研究中最困难的挑战和复杂的主题。高压实验技术的突破，使得在极端压力-温度条件下原位测量热导率成为可能。这种新技术能力，不仅为理解材料中的热传输机制提供了独特见解，而且为实现材料热性能的可逆调制提供了机会。

近日，上海高压科学技术先进研究中心陈晓嘉教授团队，撰文讨论了高压条件下的热表征技术，已经在活塞-气缸单元、多对顶砧单元和金刚石对顶砧单元等诸多设备中得到了发展，并用于表征块状和薄膜材料以及温度相关和压力相关的测量；这些高压热表征技术，已经应用于测定气体、液体和固体（包括热电材料、土壤材料和半导体材料等）的热导率以及建立相关热传输机制；还总结了各种材料的高压热导率结果，并讨论了潜在的热传输机制；此外，还关注了地球内部物质的高压和高温实验模拟应用。相关综述以“Thermal conductivity of materials under pressure”为题发表在《Nature Reviews Physics》期刊上。

图1 在环境和高压下材料中的热传输。

a| Parameters in Fourier’s law of heat conduction.b| Interfacial thermal conductance between two materials and the in- plane and out- of-plane thermal conductivity. Heterointerface contact normally includes conditions of full contact and limited contact, where some air voids are inevitably introduced during the integration (insets); both normally result in a temperature drop ΔT across the interface due to the mismatch of phonon scattering between the two different materials.c| Thermal transport at high pressures generated within a diamond anvil cell (left) and the schematic evolution of phonon density of states (DOS) and thermal conductivity with respect to pressure (right). In general, the application of pressure compresses the crystal lattice and extends the phonon frequency range, thereby, promoting the heat- carrying ability of electrons and some phonons, bringing about the modification of thermal conductivity under pressure (increasing trend, decreasing trend and anomalous trend).d| Progress in thermal conductivity measurements at high pressures. Data points are representative works; the values of pressure and year are taken from REFS. ΔT, temperature difference from the hot to the cold terminals; A, cross- sectional area; L, length of thermal transport; Q, total thermal energy of heat flow through the cross- sectional area.

图2 在压力下使用的稳态热表征方法。 

a| The Ångström method developed in the multi-anvil cell.b| The thermal grating method applied in a diamond anvil cell (DAC).c| The thermocouple method used in a DAC. T1 and T2, temperatures measured at the hot surface of the heating diamond anvil and at the cold surface of the heat- sinking diamond anvil, respectively; T3 and T4, temperatures measured near the culet of the hot anvil and the cold anvil, respectively.d| The Raman-based opto-thermal method used in a DAC111. r is the spot diameter of the excitation laser.

图3 在压力下使用的瞬态热表征方法。 

a| The transient hot- wire method developed in the piston–cylinder cell.b| The pulsed heating method developed in the multi- anvil cell.c| The pulsed- laser transient heating method applied in a diamond anvil cell.d| The time- domain thermoreflectance method and picosecond transient thermoreflectance method applied in a diamond anvil cell.

图4 气体、液体和热电材料在压力下的热导率。 

a| Hydrogen, neon, argon and methane gases; lines are simulation results. Values are taken from REFS.b| Liquids of H2O, silicone oil, methanol–ethanol mixture and toluene. Values are taken from REFS.c,d| Thermoelectric materials Pb0.99Cr0.01Se, Bi2Te3, PbTe and Sb2Te3(part c) and PdS and CuInTe2(part d), all at 300 K. Values are taken from REFS.

表1 在压力下，各种气体、液体及固体材料的热导率研究汇总

BTE, Boltzmann transport equation; Comp., compression; DAC, diamond anvil cell; DFT, density functional theory; MD, molecular dynamics; PBTE, Peierls–Boltzmann transport equation; TDTR, time- domain thermoreflectance; TH, pulsed- laser transient heating; TTR, transient thermoreflectance.

图5 地球材料在压力下的热导率。

a| Earth core materials of iron and iron–silicon alloys up to 120 GPa at 300 K.b| Earth core materials of iron and iron–silicon alloys up to 144 GPa and 3,300 K. The values are taken from REFS. The lines are to guide the eye.c| Earth mantle materials for typical minerals of MgO and (Mg, Fe)O. The values are taken from REFS.d| Earth materials for typical core–mantle boundary (CMB) minerals of MgSiO3, (Mg, Fe)SiO3and (Mg, Fe, Al)SiO3up to 144 GPa and 3,700 K. The values are taken from REFS. PPv, post- perovskite; Pv, perovskite.

图6 半导体电子材料在压力下的热导率。

a| Semiconductor materials of Si and Si0.991Ge0.009measured using time- domain thermoreflectance near 300 K at pressures up to 45 GPa.b| Wide-bandgap CuCl measured using the transient hot- wire technique within the pressure range 0.5–2.7 GPa and temperature range 100–480 K.c| Normalized thermal conductivity calculated from first principles for binary compound semiconductors of GaAs, SiC, BP and BN with an increasing trend; BAs, BeTe and BSb with a decreasing trend; and BeSe with a non- monotonic trend.d| Thermal conductivity of the 2D material MoS2. hcp, hexagonal close-packed; Prim. hex, primitive hexagonal.

原文信息：

Zhou, Y., Dong, ZY., Hsieh, WP. et al. Thermal conductivity of materials under pressure. Nat Rev Phys (2022).

https://doi.org/10.1038/s42254-022-00423-9