Nature Physical Review: High-pressure thermal conductivity - Dr. Xiaojia Chen

FEBRUARY 21, 2022

Measuring and understanding the thermal conductivities of materials is essential for many practical applications we use daily, but what happens under high pressure? A new review paper, "Thermal Conductivity of Materials under Pressure," published recently in Nature Reviews Physics (online February 21st) by HPSTAR’s Dr. Xiaojia Chen summarizes the recent breakthroughs in high-pressure experimental techniques that have enabled in situ thermal conductivity measurements at extreme pressure-temperature conditions.

The thermal conductivities of materials are extremely important for many practical applications, such as understanding the thermal balance and history of the Earth or energy conversion in devices and the thermal management of electronics. However, measuring the thermal conductivity of materials under pressure and understanding the associated thermal transport mechanisms remains exceptionally complex. 

Now, this crucial review paper summarizes the recent breakthroughs in high-pressure experimental techniques that have enabled in situ thermal conductivity measurements at extreme pressure-temperature conditions. Moreover, the paper systematically introduces and summarizes the thermal conductivity of gaseous, liquid, and solid materials under high pressure and explores their measurement methods and research results.

Collaborating with fellow experts, Dr. Wenbin Xie of the Institute of Geological Sciences, Academia Sinica, Taiwan, and Dr. Alexander F. Goncharov of the Earth and Planetary Laboratory of the Carnegie Institution in Washington, USA, Dr. Chen and his team offer a comprehensive summary of thermal conductivity and its related challenges. Recent progress in high-pressure characterization techniques developed to determine the thermal conductivity of gases, liquids, and solids, and establish the correlated thermal transport mechanisms is discussed. Apparatus such as piston–cylinder cells, multi-anvil cells, and diamond anvil cells for both bulk and thin-film materials and both temperature-dependent and pressure-dependent measurements are appraised. Finally, practical applications of high-pressure and high-temperature experimental simulations of materials in the Earth’s interior are offered.

Caption: Spectral characterization method of thermal conductivity under high pressure and evolution of thermal conductivity with pressure.

Although much of this research is in its infancy, it is a rapidly growing area of interest. Even more advanced characterization techniques are necessary to overcome the complex challenges of determining the pressure-dependent thermophysical properties of materials. However, there is great potential for exceptional results with practical applications, like informing new thermal management techniques for the electronic devices that we increasingly rely on in our everyday lives.

Responding to the paper, HPSTAR Director Dr. Ho-Kwang Mao said, “These advances in high-pressure thermal conductivity measurement technology provides a unique perspective for revealing and understanding the thermal conduction behavior of materials like never before, giving us a comprehensive understanding of the physical and chemical properties of materials that may lead to many important scientific discoveries in the future".

《自然物理评论》(Nature Reviews Physics)于2月21日在线发表了题为“Thermal conductivity of materials under pressure”的长篇综述，系统介绍和总结了气态、液态和固态材料在高压下的热导率测量方法和研究结果，以及相关的热输运机制，并对未来研究方向进行了展望。压力作为一个物理维度和窗口以调节材料的物理和化学性质，带来了丰富多彩和前所未有的现象和结果，极大地促进了人们对压缩条件下特殊性质的认知，不仅用以检验难以在常规条件下获取的技术参数和理论，更将高压下实现的卓越特性在常规压力条件下俘获和重现。尽管高压技术在过去一个世纪中在材料性能的表征和研究方面取得了突破性的进展，然而高压下材料热导率的准确测量长期以来一直是高压研究的难题，至上世纪末热导率的测量仍受限于几个GPa的范围，远比同期其他技术标征落后将近2个数量级。极大地限制了材料高压下热传导、扩散和管理的研究，制约了材料热性质的理解和发展。大的技术瓶颈突破来源于光谱测量手段的引入，超过10 GPa热导率数据的获取也只是近15年的事情，由于论文作者主要参与了这些技术的发展和推动，在这篇综述中他们提供了详实的技术细节和应用场景 。