{"title":"Novel Ultrahard Carbon Allotropes from Crystal Chemistry and First Principles: Rhombohedral ene-C21 and yne-C24","authors":"Samir F. Matar, Vladimir L. Solozhenko","doi":"10.3103/S1063457623060072","DOIUrl":null,"url":null,"abstract":"<p>Rhombohedral <i>ene</i>-C<sub>21</sub> and <i>yne</i>-C<sub>24</sub>, characterized by the presence of C=C and C≡C bonds, respectively, inserted into the 9R diamond polytype C<sub>18</sub>, are proposed as novel ultrahard carbon allotropes from crystal chemistry and first principles. Like 9R C<sub>18</sub>, they belong to the <b>cfe</b> topology characteristic of layered SiC polytypes. With ultrahard properties approaching those of diamond and lonsdaleite, <i>ene</i>-C<sub>21</sub> and <i>yne</i>-C<sub>24</sub> are dynamically stable with phonon signatures identifying C=C and C≡C high frequency vibrations similar to molecular allene and acetylene. The electronic band structures correspond to insulating C<sub>18</sub>, metallic <i>ene</i>-C<sub>21</sub> and semiconducting <i>yne</i>-C<sub>24</sub>.</p>","PeriodicalId":670,"journal":{"name":"Journal of Superhard Materials","volume":"45 6","pages":"405 - 414"},"PeriodicalIF":1.2000,"publicationDate":"2024-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Superhard Materials","FirstCategoryId":"88","ListUrlMain":"https://link.springer.com/article/10.3103/S1063457623060072","RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Rhombohedral ene-C21 and yne-C24, characterized by the presence of C=C and C≡C bonds, respectively, inserted into the 9R diamond polytype C18, are proposed as novel ultrahard carbon allotropes from crystal chemistry and first principles. Like 9R C18, they belong to the cfe topology characteristic of layered SiC polytypes. With ultrahard properties approaching those of diamond and lonsdaleite, ene-C21 and yne-C24 are dynamically stable with phonon signatures identifying C=C and C≡C high frequency vibrations similar to molecular allene and acetylene. The electronic band structures correspond to insulating C18, metallic ene-C21 and semiconducting yne-C24.
期刊介绍：
Journal of Superhard Materials presents up-to-date results of basic and applied research on production, properties, and applications of superhard materials and related tools. It publishes the results of fundamental research on physicochemical processes of forming and growth of single-crystal, polycrystalline, and dispersed materials, diamond and diamond-like films; developments of methods for spontaneous and controlled synthesis of superhard materials and methods for static, explosive and epitaxial synthesis. The focus of the journal is large single crystals of synthetic diamonds; elite grinding powders and micron powders of synthetic diamonds and cubic boron nitride; polycrystalline and composite superhard materials based on diamond and cubic boron nitride; diamond and carbide tools for highly efficient metal-working, boring, stone-working, coal mining and geological exploration; articles of ceramic; polishing pastes for high-precision optics; precision lathes for diamond turning; technologies of precise machining of metals, glass, and ceramics. The journal covers all fundamental and technological aspects of synthesis, characterization, properties, devices and applications of these materials. The journal welcomes manuscripts from all countries in the English language.
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