2017年12月1日
Earlier this year, a technique involving moderately high temperatures, high pressures, and a small amount of glassy carbon as starting material was used to synthesize amorphous diamond for the first time. A father-son team from Clemson University has now successfully calculated many basic physical properties for this new substance, including elastic constants and other related quantities. The study findings are reported this week inAIP出版sApplied Physics Letters.
Diamond is a type of pure carbon where the atoms are positioned in a crystal lattice, with each carbon atom enclosed by four other carbons at the corners of a tetrahedron. The carbon-carbon bonds in diamond are sp3 bonds. The arrangement of tetrahedral structures is repeated over long distances in a diamond crystal, generates a solid material with high temperature stability. Therefore, diamond is a valuable gemstone as well as a material with many technological uses.
另一方面，无定形碳在无定形或无序基质中具有不同的SP3键碳的分数。无定形结构产生极为理想的机械性能。无定形碳中的粘结水平并不像纯钻石中的那样。碳碳键的部分是SP2型的，在其他碳类型（例如石墨）中发现。
SP3键晶锗和无定形硅已经闻名了多年，通常在晶体管，薄膜传感器和光伏电源型以及其他高科技应用中使用。因此，确定生成无定形钻石的方法非常感兴趣，以保持大量的SP3键。尽管今年早些时候报道的工作仅此而已，但尚未通常可以进行测试。初始测试确实表明这些无定形钻石相当致密，光学透明且强烈。
The father-son team, Arthur and John Ballato, have stepped into this knowledge gap in order to calculate some physical properties that are not yet measured for this new type of diamond."We employed a modeling approach by which one can use the properties of crystalline diamond to deduce the properties of the glassy diamond analog,"stated Ballato.“在这项工作中，我们从晶体钻石的测得的特性中推断出了这种新钻石的弹性特性。”
他们使用的过程涉及一个晶体的计算机模型，该模型在计算上均质化以使物质的无定形版本。晶体模型使用简单的经典物理学，并将碳碳键解释为弹簧。所使用的均质化过程称为Voigt-Reuss-Hill（VRH）技术。
The Ballatos computed many important bulk properties, including Poisson's ratio, Young's modulus, and other elastic constants for the substance by using this technique. They used the VRH homogenization technique in earlier works to study glassy sapphire and other materials of interest for use in high power lasers. The VRH approach is more straightforward and simpler than sophisticated quantum mechanical techniques that are currently available, but the properties determined in this work can serve as a baseline, for more sophisticated, but costly modeling, and for future experimental measurements.