Superhard yne-diamond
首发时间:2014-05-15
Abstract:Two sp+sp3-hybridized yne-diamond (YD) allotropes are designed by employing first-principle calculations. The YDs are constructed by replacing half carbon single bonds (C-C) along the <001> direction in 2H-diamond and 4H-diamond with acetylenic linkages (C-C≡C-C). Both YDs are energetically more favorable than experimental graphdiyne, theoretical graphynes (e.g., α-, β-, and 6,6,12-graphyne), and T-carbon. The YDs are confirmed to be mechanically and dynamically stable. Different from the recently proposed semiconductive YD based on cubic diamond (i.e. Y-carbon), electronic band structure calculations show that both YDs we proposed are semimetals. Mechanically, two YDs inherit the superhardness and high tensile strength from the parent diamonds. We hope our present findings can be useful in guiding the design and syntheses of superhard and semimetallic carbon materials.
keywords: carbon materials yne-diamond semimetallicity superhardness
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超硬金刚石炔
摘要:通过第一性原理计算,理论设计了两种sp+sp3杂化的金刚石炔结构。二者是通过用乙炔链(C-C≡C-C)替换2H-金刚石和4H-金刚石<001>方向二分之一的单键(C-C)形成的。二者比试验合成的石墨二炔、理论计算的石墨炔(比如 α-石墨炔、β-石墨炔、6,6,12-石墨炔等)以及T-碳具有更高的热力学稳定性。计算表明两种金刚石炔满足动力学稳定和热力学稳定条件。电子能带计算表明,二者都具有半金属性,这与前人基于立方金刚石提出的金刚石炔(即Y-碳)大大不同,Y-碳表现为半导体性。两种金刚石炔遗传了母相金刚石超高硬度和高的抗拉强度的特点。综上所述,金刚石炔有望在设计和合成新型超硬的、金属性的碳材料方面发挥重要作用。
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No.4596362976573139****
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