Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, 22904, USA.
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA.
Adv Mater. 2018 Dec;30(51):e1805004. doi: 10.1002/adma.201805004. Epub 2018 Oct 17.
Manipulating a crystalline material's configurational entropy through the introduction of unique atomic species can produce novel materials with desirable mechanical and electrical properties. From a thermal transport perspective, large differences between elemental properties such as mass and interatomic force can reduce the rate at which phonons carry heat and thus reduce the thermal conductivity. Recent advances in materials synthesis are enabling the fabrication of entropy-stabilized ceramics, opening the door for understanding the implications of extreme disorder on thermal transport. Measuring the structural, mechanical, and thermal properties of single-crystal entropy-stabilized oxides, it is shown that local ionic charge disorder can effectively reduce thermal conductivity without compromising mechanical stiffness. These materials demonstrate similar thermal conductivities to their amorphous counterparts, in agreement with the theoretical minimum limit, resulting in this class of material possessing the highest ratio of elastic modulus to thermal conductivity of any isotropic crystal.
通过引入独特的原子种类来操纵晶体材料的构象熵，可以产生具有理想力学和电学性能的新型材料。从热输运的角度来看，原子质量和原子间作用力等元素性质的巨大差异会降低声子传热的速率，从而降低热导率。材料合成的最新进展使得熵稳定陶瓷的制造成为可能，这为理解极端无序对热输运的影响开辟了道路。通过测量单晶熵稳定氧化物的结构、力学和热学性能，表明局部离子电荷无序可以有效地降低热导率而不牺牲力学刚度。这些材料的热导率与非晶态材料相似，符合理论最小值，这使得这类材料具有各向同性晶体中弹性模量与热导率之比最高的特点。
