{"title":"Novel Ultrahard Monoclinic Carbon Allotropes from Crystal Structure Engineering and First Principles","authors":"S. F. Matar, V. L. Solozhenko","doi":"10.3103/S1063457625060024","DOIUrl":null,"url":null,"abstract":"<p>Two novel monoclinic (space group <i>C</i>2/<i>c</i>) carbon allotropes, <i>m</i>-C<sub>8</sub>, with ths and dia topologies, were proposed through crystal structure engineering. The ths allotrope is built by three-dimensional tiling of trigonal carbon units, which is different from tiling of <i>C4</i> tetrahedra in the case of dia <i>m</i>‑C<sub>8</sub>. Structural studies were supported by density functional theory (DFT)-based calculations of ground state structures and energy-derived properties. Extensive investigations of cohesive energies, energy-volume equations of state, mechanical (elastic constants and moduli, hardness) and dynamical (e.g., phonons) properties revealed the new allotropes to be cohesive and stable both mechanically and dynamically. Although they are metastable compared to diamond, their formation is possible under non-equilibrium conditions as a result of alternative metastable behavior.</p>","PeriodicalId":670,"journal":{"name":"Journal of Superhard Materials","volume":"47 6","pages":"430 - 438"},"PeriodicalIF":1.2000,"publicationDate":"2025-12-23","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/S1063457625060024","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
Two novel monoclinic (space group C2/c) carbon allotropes, m-C8, with ths and dia topologies, were proposed through crystal structure engineering. The ths allotrope is built by three-dimensional tiling of trigonal carbon units, which is different from tiling of C4 tetrahedra in the case of dia m‑C8. Structural studies were supported by density functional theory (DFT)-based calculations of ground state structures and energy-derived properties. Extensive investigations of cohesive energies, energy-volume equations of state, mechanical (elastic constants and moduli, hardness) and dynamical (e.g., phonons) properties revealed the new allotropes to be cohesive and stable both mechanically and dynamically. Although they are metastable compared to diamond, their formation is possible under non-equilibrium conditions as a result of alternative metastable behavior.
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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