Fluid Synthesis of Cubic Graphite

The paper presents X-ray data on the synthesis of cubic graphite and other polymorphic modifications of carbon by the reverse Boudoir reaction by the fluid method (FS, patent of Ukraine) using supercritical CO2 as a fluid and artificial diamond ASM1/0, carbon black, and metal powders as starting materials. Regardless of the type of starting material, cubic graphite was always formed as a result of the synthesis. It is shown that experiments on the fluid synthesis of carbon phases confirm some analogy with its formation in natural conditions. The new results expand the picture of the phase formation of carbon structures and fit into the framework of the proposed new model. The carbon phase cubic graphite (Gc) under conditions of fluid supercritical synthesis in a CO2 environment is easily formed (more than 50 samples were obtained from experiments with its inclusion) from many carbon compounds as starting materials. Two possible models of the phase structure are considered — as SCF-С24 and C96. In high gas pressure equipment at P less than 1 GPa (less than 104 atmospheres) and T less than 1000ºС, cubic graphite of varying degrees of perfection was obtained in many experiments. Carbon dioxide CO2 was used as a supercritical fluid at various parameters of pressure, temperature and time. The schematic diagram of the experimental equipment for fluid synthesis is presented in many of our published works. One of the synthesized samples, obtained using magnesium, is a carbon material with cubic graphite and exhibits the largest number of clear lines in X-ray patterns of all the starting substances we used: 3.28а, 3.24а, 3.16а, 2.88а, 2.51а, 2.46а, 1.970а, 1.914а, 1.635а, 1.467а. The carbon phase cubic graphite is a stable modification of carbon.