arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2012.12864cond-mat.mtrl-sci
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高熵稀土四硼化物

High-Entropy Rare Earth Tetraborides

Mingde Qin, Qizhang Yan, Haoren Wang, Kenneth S. Vecchio, Jian Luo

摘要:

首次成功合成了六个具有四硼化铀B4原型结构的高熵稀土四硼化物。试样由元素前驱体通过高能球磨和原位反应放电等离子烧结制备。烧结样品的相对密度>98%,没有可检测到的氧化物杂质(尽管在一些组合物中存在少量的六硼化物)。在组合物(Y $_{0.2}$ Nd $_{0.2}$ Sm $_{0.2}$ Gd $_{0.2}$ Tb $_{0.2}$)B $_{4}$中没有观察到可检测的第二相,其在微米级和纳米级都被证明是均匀的。在9.8 N的标准压痕载荷下,维氏显微硬度被确定为约13-15 GPa。一个科学上有趣的观察是由来自混合平均规则的各向异性晶格畸变表示的。本工作通过制备一类具有独特的四方准层状晶体结构的高熵硼化物,扩展了高熵陶瓷的家族。

英文摘要:

Six high-entropy rare earth tetraborides of the tetragonal UB4-prototyped structure have been successfully synthesized for the first time. The specimens are prepared from elemental precursors via high-energy ball mill and in-situ reactive spark plasma sintering. The sintered specimens are >98% in relative densities without detectable oxide impurities (albeit the presence of minor hexaborides in some compositions). No detectable secondary phase is observed in the composition (Y$_{0.2}$Nd$_{0.2}$Sm$_{0.2}$Gd$_{0.2}$Tb$_{0.2}$)B$_{4}$, which is proven homogeneous at both microscale and nanoscale. The Vickers microhardness are determined to be ~13-15 GPa at a standard indentation load of 9.8 N. A scientifically interesting observation is represented by the anisotropic lattice distortion from the rule-of-mixture averages. This work expands the family of high-entropy ceramics via fabricating a new class of high-entropy borides with a unique tetragonal quasi-layered crystal structure.

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