Open AccessEffect of Oxygen on Diamond Crystallization in Metal–Carbon Systems
Author(s) -
Yuri N. Palyanov,
Yuri M. Borzdov,
Igor N. Kupriyanov,
Yuliya V. Bataleva,
Denis V. Nechaev
Publication year - 2020
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.0c02130
Subject(s) - crystallization , diamond , oxygen , materials science , wüstite , crystal (programming language) , graphite , carbon fibers , chemical engineering , solubility , nickel , metal , limiting oxygen concentration , crystal growth , inorganic chemistry , analytical chemistry (journal) , crystallography , chemistry , metallurgy , oxide , organic chemistry , composite material , composite number , computer science , engineering , programming language
In this article, we report the influence of oxygen concentration in the transition-metal solvent-catalyst on the crystallization processes, morphology, and defect-and-impurity content of diamond crystals. In a series of experiments, the concentration of oxygen ( C O ) in the growth system was varied by adding Fe 2 O 3 to the charge, and the other parameters and conditions of the growth were constant: Ni 7 Fe 3 solvent-catalyst, P = 6.0 GPa, T = 1400 °C, and duration of 40 h. It is found that on increasing C O in the growth system from 0 to 10 wt %, the crystallization of diamond proceeds through the following stages: single crystal → block crystal → spontaneous crystals → aggregate of block crystals and twin crystals. At C O ≥ 5 wt %, diamond crystallizes jointly with wustite (FeO) and metastable graphite. The oxygen solubility in the iron-nickel melt is estimated at about 2 wt %. With increasing oxygen content in the system, the range of nitrogen concentrations in diamonds crystallized in one experiment significantly broadens with the maximum nitrogen concentrations being increased from 200-250 ppm in the experiment without O additives to 1100-1200 ppm in the experiment with 10 wt % O added. The established joint growth of diamond and wustite suggests possible crystallization of natural diamonds in the Fe-Ni-O-C system over a wide range of oxygen concentrations up to 10 wt %.