Premium
First‐Principles Insight into the Composition‐Dependent Structure and Properties of γ‐Alon
Author(s) -
Tu Bingtian,
Wang Hao,
Liu Xiao,
Wang Weimin,
Fu Zhengyi
Publication year - 2014
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.13051
Subject(s) - spinel , solid solution , lattice constant , materials science , crystal structure , crystallography , thermodynamics , analytical chemistry (journal) , chemistry , diffraction , physics , chromatography , optics , metallurgy
Spinel type Aluminum oxynitride (γ‐alon) solid solution exists in the Al 2 O 3 ‐rich region of AlN – Al 2 O 3 systems. The first‐principles calculations facilitate our investigations on composition‐dependence of structure and properties in γ‐alon without the limit of experimental solubility. The constant anion crystal structure of γ‐alon was described as the solid solution of spinel phase γ‐ Al 2 O 3 and the ideal Al 3 O 3 N with formula of Al (8+ x )/3 O 4− x N x (0 ≤ x ≤ 1). The unit cell expands with increasing Al 3 O 3 N composition. The lattice parameter increases nonlinearly with the composition of Al 3 O 3 N , which deviates from Vegard's law. As x increases, the anions dilate from the Al IV along (1 1 1) direction, and two new narrow peaks (approximate –12.7 and –0.3 eV) become stronger and the conduction band presents a downward shift to low energy in the TDOS. The absorption edge in the UV region of ε 2 (ω) present slight red‐shift of 0.5 eV as x increases. Because the compressibility was improved by expansion of coordination polyhedron, the elastic properties were just slightly enhanced as the nitrogen concentration increases. It is suggested that the notable enhancement of mechanical properties in γ‐alon may be difficult to yield by varying the content of substituted nitrogen atoms. The calculated results provide the basis for understanding the crystal structure and intrinsic properties of γ‐alon with different compositions.