Формирование структуры гексагонального алмаза: ab initio расчеты

Abstract

Modeling of the structure formation of hexagonal diamond from graphite and cubic diamond was performed using the density functional theory method. The transformation of orthorhombic AB graphite into hexagonal diamond can occur as a result of uniaxial compression at pressures above 61 GPa. For the formation of hexagonal diamond from AA graphite, the pressure must exceed 57 GPa. Another possible way to obtain hexagonal diamond is uniaxial compression of cubic diamond at pressures from 300 to 380 GPa. The data of theoretical calculations were used to interpret the diffraction data obtained as a result of X-ray diffraction and electron microscopic analysis of natural and synthetic diamond-like materials. It was found that crystals with the ideal cubic and hexagonal structure are not contained in diamond-like carbon materials, and their structure is characterized by random packing of molecular layers.