РОССИЙСКАЯ АКАДЕМИЯ НАУК

УРАЛЬСКОЕ ОТДЕЛЕНИЕ

ИНСТИТУТ ХИМИИ TBEPДОГО ТЕЛА
   
| | | | |
| | | |
 29.08.2020   Карта сайта     Language По-русски По-английски
Новые материалы
Экология
Электротехника и обработка материалов
Медицина
Статистика публикаций


29.08.2020















Ultrahard nanomaterials: myths and reality 

 
Volume 63 (2020) 

Number 6 

Pages 523–544 
V V Brazhkin



Vereshchagin Institute for High Pressure Physics, Russian Academy of Sciences
 

Abstract

The last 25 years has witnessed a wealth of publications on the creation of carbon materials whose compression bulk modulus and hardness are much higher than those of diamond. This review presents a critical analysis of these studies. Three groups of myths that have emerged lately are discussed. The first is related to the possibility of creating materials whose bulk moduli are significantly higher than those of diamond. The second group is devoted to `experimentally measured' values of hardness, much higher than that of diamond. The third includes alleged `theoretical' grounds for a several-fold (!) increase in the hardness of covalent substances due to the effects of quantum confinement. It is shown that materials whose elastic moduli significantly exceed those of diamond cannot in principle be produced under normal conditions. Issues surrounding the quantitative measurement of hardness are discussed; it is noted that the creation of obstacles to the movement of dislocations in nanomaterials may allow a 20-40 % increase in the effective measured hardness of ultrahard materials. It is emphasized that alternative hypothetical approaches to increase hardness, for example, due to quantum confinement, actually have no physical grounds whatsoever. The highest mechanical characteristics of diamond are associated with reliably established physical laws, and any assertions regarding possible obtainment of materials whose elastic characteristics or hardness are several times greater than those of diamond may not be regarded as reliable to any extent or even science-based.


Keywords:elastic moduli, hardness, carbon materials, nanostructures, quantum confinement









DOI https://doi.org/10.3367/UFNe.2019.07.038635


Дизайн и программирование N-Studio 
А Б В Г Д Е Ё Ж З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ъ Ы Ь Э Ю Я
  • Chen Wev .  honorary member of ISSC science council

  • Harton Vladislav Vadim  honorary member of ISSC science council

  • Lichtenstain Alexandr Iosif  honorary member of ISSC science council

  • Novikov Dimirtii Leonid  honorary member of ISSC science council

  • Yakushev Mikhail Vasilii  honorary member of ISSC science council

  • © 2004-2021 ИХТТ УрО РАН
    беременность, мода, красота, здоровье, диеты, женский журнал, здоровье детей, здоровье ребенка, красота и здоровье, жизнь и здоровье, секреты красоты, воспитание ребенка рождение ребенка,пол ребенка,воспитание ребенка,ребенок дошкольного возраста, дети дошкольного возраста,грудной ребенок,обучение ребенка,родить ребенка,загадки для детей,здоровье ребенка,зачатие ребенка,второй ребенок,определение пола ребенка,будущий ребенок медицина, клиники и больницы, болезни, врач, лечение, доктор, наркология, спид, вич, алкоголизм православные знакомства, православный сайт творчeства, православные рассказы, плохие мысли, православные психологи рождение ребенка,пол ребенка,воспитание ребенка,ребенок дошкольного возраста, дети дошкольного возраста,грудной ребенок,обучение ребенка,родить ребенка,загадки для детей,здоровье ребенка,зачатие ребенка,второй ребенок,определение пола ребенка,будущий ребенок