Sharma Prince, Balasubramanian Ganesh
Institute for Functional Materials & Devices, Lehigh University, Bethlehem, Pennsylvania 18015, United States.
Chem Mater. 2023 Sep 15;35(18):7511-7520. doi: 10.1021/acs.chemmater.3c01086. eCollection 2023 Sep 26.
Borides are extensively employed in applications demanding exceptionally high hardness, which arises from the unique and strong crystallographic arrangement of boron atoms therein. Addition of multiprincipal elements in borides is expected to enhance their structural properties due to lattice distortion and high configurational entropy. In contrast, we unravel a phenomenon of elastic softening in refractory multicomponent borides from first-principle predictions, which concur with experimentally determined metrics in their single-phase multiprincipal element counterparts. The reductions in the bulk and Young's modulus of these compounds are attributed to the lengthening and distortion of the boron-boron bonds and angles, but more critically to the perturbation in the charge densities arising from the different cations and the consequential increase in statistical weights of the configuration states of the transition metals present in the boride..
硼化物广泛应用于要求具有极高硬度的领域，这种硬度源于其中硼原子独特而强大的晶体结构排列。由于晶格畸变和高组态熵，预计在硼化物中添加多主元元素会增强其结构性能。相比之下，我们通过第一性原理预测揭示了难熔多组分硼化物中的弹性软化现象，这与在单相多主元元素对应物中通过实验确定的指标一致。这些化合物的体模量和杨氏模量的降低归因于硼 - 硼键和键角的延长及畸变，但更关键的是不同阳离子引起的电荷密度扰动以及硼化物中存在的过渡金属组态状态统计权重的相应增加。
