Role of bonding and coordination in the atomic structure and energy of diamond and silicon grain boundaries

Journal Article · Sat Aug 01 04:00:00 EDT 1998 · Journal of Materials Research

DOI:https://doi.org/10.1557/JMR.1998.0292· OSTI ID:641517

Keblinski, P; Wolf, D; Phillpot, S R ^[1]; Keblinski, P; Gleiter, H ^[2]

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1. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Forschungszentrum Karlsruhe, 76021 Karlsruhe (Germany)

The high-temperature equilibrated atomic structures and energies of large-unit-cell grain boundaries (GB{close_quote}s) in diamond and silicon are determined by means of Monte-Carlo simulations using Tersoff{close_quote}s potentials for the two materials. Silicon provides a relatively simple basis for understanding GB structural disorder in a purely sp{sup 3} bonded material against which the greater bond stiffness in diamond combined with its ability to change hybridization in a defected environment from sp{sup 3} to sp{sup 2} can be elucidated. We find that due to the purely sp{sup 3}-type bonding in Si, even in highly disordered, high-energy GB{close_quote}s at least 80{percent} of the atoms are fourfold coordinated in a rather dense confined amorphous structure. By contrast, in diamond even relatively small bond distortions exact a considerable price in energy that favors a change to sp{sup 2}-type local bonding; these competing effects translate into considerably more ordered diamond GB{close_quote}s; however, at the price of as many as 80{percent} of the atoms being only threefold coordinated. Structural disorder in the Si GB{close_quote}s is therefore partially replaced by coordination disorder in the diamond GB{close_quote}s. In spite of these large fractions of three-coordinated GB carbon atoms, however, the three-coordinated atoms are rather poorly connected amongst themselves, thus likely preventing any type of graphite-like electrical conduction through the GB{close_quote}s. {copyright} {ital 1998 Materials Research Society.}

• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 641517
• Journal Information: Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 8 Vol. 13; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL BONDS
COORDINATION NUMBER
DIAMONDS
ELECTRIC CONDUCTIVITY
ELECTRONIC STRUCTURE
GRAIN BOUNDARIES
SILICON