From soft to superhard: fifty years of experiments on cold-compressed graphite
In recent years there have been numerous computational studies predicting the nature of cold-compressed graphite yielding a proverbial alphabet soup of carbon structures (e.g., bct-C4, K4-, M-, H-, R-, S-, T-, W- and Z-carbon). Although theoretical methods have improved, the inherent nature of graph...
Збережено в:
| Дата: | 2012 |
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| Автори: | , |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Інститут надтвердих матеріалів ім. В.М. Бакуля НАН України
2012
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| Назва видання: | Сверхтвердые материалы |
| Теми: | |
| Онлайн доступ: | http://dspace.nbuv.gov.ua/handle/123456789/126008 |
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | From soft to superhard: fifty years of experiments on cold-compressed graphite / Y. Wang, K.K.M. Lee // Сверхтвердые материалы. — 2012. — № 6. — С. 25-39. — Бібліогр.: 72 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| Резюме: | In recent years there have been numerous computational studies predicting the nature of cold-compressed graphite yielding a proverbial alphabet soup of carbon structures (e.g., bct-C4, K4-, M-, H-, R-, S-, T-, W- and Z-carbon). Although theoretical methods have improved, the inherent nature of graphite (i.e., low-Z) and the subsequent room-temperature, high-pressure phase transition (i.e., low symmetry, nanocrystalline and sluggish), make experimental measurements difficult to execute and interpret even with the current technology of 3rd generation synchrotron sources. The room-temperature, high-pressure phase transition of graphite has been detected by numerous kinds of experiments over the past fifty years, such as electrical resistance measurements, optical microscopy, X-ray diffraction, inelastic X-ray scattering, and Raman spectroscopy. However, the identification and characterization of high-pressure graphite is replete with controversy since its discovery more than fifty years ago. Recent experiments confirm that this phase has a monoclinic structure, consistent with the M-carbon phase predicted by theoretical computations. Meanwhile, experiments demonstrate that the phase transition is sluggish and kinetics is important in discerning the phase boundary. Additionally, the post-graphite phase appears to be superhard with hardness comparable to that of diamond. |
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