Superhard Nitride-Based Nanocomposites: Role of Interfaces and Effect of Impurities

Shiqiang Hao, Bernard Delley, Stan Veprek, and Catherine Stampfl
Phys. Rev. Lett. 97, 086102 – Published 24 August 2006

Abstract

Recently, a hardness similar to that of diamond has been reported for a quasiternary, nitride-based nanocomposite. The related, quasibinary nanocomposite “ncTiN/aSi3N4,” which may be regarded as the prototype of the family of superhard ncmetalN/aSi3N4 systems, also exhibits a significant hardness enhancement. Extensive density-functional theory calculations indicate that the superhardness is related to the preferential formation of TiN(111) polar interfaces with a thin βSi3N4-derived layer. The strength of TiN in the 111 direction is similar to that of the weakest bonding direction in diamond. Oxygen impurities cause a significant reduction of the interface strength.

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  • Received 20 April 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.086102

©2006 American Physical Society

Authors & Affiliations

Shiqiang Hao1, Bernard Delley2, Stan Veprek3, and Catherine Stampfl1

  • 1School of Physics, The University of Sydney, Sydney NSW 2006, Australia
  • 2Paul Scherrer Institut, WHGA/123, CH-5232 Villigen PSI, Switzerland
  • 3Department of Chemistry, Technical University Munich, Lichtenbergstrasse 4, D-85747 Garching, Germany

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Issue

Vol. 97, Iss. 8 — 25 August 2006

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