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First‐principles investigation of the thermodynamic stability of M B 2 materials surfaces ( M = Ti/Zr/Hf)
Author(s) -
Zhang Yanhui,
Sanvito Stefano
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15547
Subject(s) - ceramic , materials science , surface energy , chemical stability , thermodynamics , metal , matrix (chemical analysis) , cleavage (geology) , transition metal , surface (topology) , composite material , ceramic matrix composite , nanotechnology , crystallography , chemistry , metallurgy , physics , catalysis , geometry , fracture (geology) , mathematics , biochemistry
Abstract Some of the renewed interest in transition metal diborides ( M B 2 , M = Ti/Zr/Hf) arises from their potential use as matrices in ultrahigh‐temperature ceramic matrix composites ( UHTCMC s). Crucial to the understanding of such composites is the study of the fiber/matrix interfaces, which in turn requires a deep knowledge of the surface structures and the thermodynamics of the matrix material. Here we investigate the surface stability of M B 2 compounds by first‐principles calculations. Five surfaces are stabilized when going from a M ‐rich to a B‐rich environment, respectively (0001) M , (10 1 ¯ 0) M , (10 1 ¯ 1) B( M ) , (11 2 ¯ 3) M and (0001) B , with the highly stable (10 1 ¯ 0) M , (10 1 ¯ 1) B( M ) and (11 2 ¯ 3) M surfaces being discussed here for the first time. The mechanism behind the surface stability is analyzed in terms of cleavage energy, surface strain and surface bonding states. Our results provide important information for a better understanding of the most likely surfaces exposed to the fibers in UHTCMC s, thereby for the construction of reliable interfaces and ultimately UHTCMC s models.