Thermal conductivity of equiatomic high-entropy diboride ceramics with 5-9 cations

As a new type of high-entropy material, most of the current work has focused on the synthesis and characterization of mechanical properties of high-entropy diboride ceramics (HEBs). In this work, single-phase HEBs with 5-9 cations were prepared by spark plasma sintering with self-synthesized HEB powders through the boro/carbothermal reduction method. The distribution of the metal elements in the obtained HEBs was homogeneous. Due to the phonon scattering caused by the inherent lattice distortion in the HEBs, the thermal conductivity of the ceramics decreased with the increased configurational entropy or the number of cation kinds. However, this study reveals that the degree of reduction in thermal conductivity for the HEBs demonstrate a weakened tendency with cation kinds of more than 6.