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Bond Energetics at Intergranular Interfaces in Alumina‐Doped Silicon Nitride
Author(s) -
Painter Gayle S.,
Becher Paul F.,
Sun Ellen Y.
Publication year - 2002
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/j.1151-2916.2002.tb00040.x
Subject(s) - materials science , sialon , nitride , intergranular corrosion , aluminium , silicon nitride , silicon , ceramic , epitaxy , chemical bond , doping , grain boundary , layer (electronics) , crystallography , composite material , metallurgy , microstructure , chemistry , organic chemistry , optoelectronics
In Si 3 N 4 ceramics sintered with Al 2 O 3 , the interfacial strength between the intergranular glass and the reinforcing grains has been observed to increase with increases in the aluminum and oxygen content of the epitaxial β‐Si 6‐ z Al z O z N 8– z layer that forms on the Si 3 N 4 grains. This has been attributed to the formation of a network of strong bonds (cross bonds) that span the glass‐crystalline interface. This proposed mechanism is considered further in light of first‐principles atomic cluster calculations of the relative stabilities of bridge and threefold‐bonded atomic fragments chosen to represent compositional changes at the glass/Si 3 N 4 grain interface. Calculated binding energies indicate Al‐N binding is favorable at the Si 3 N 4 grain surface, where aluminum occupancy can promote the growth of SiAlON, further enhancing the cross‐bonding mechanism of interfacial strengthening.