Elastic constants of oxynitride aluminum spinel phases

Okeke, Onyekwelu U.; Lowther, J. E.

doi:10.1016/j.cplett.2010.06.015

Cited by 11 publications

(8 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The band gaps predicts by the DFT are smaller than experimental data, which means that our theoretical values from 3.79 to 4.20 eV underestimate the real band gap of γ‐alon. Comparing with previous calculated and experimental results, our theoretical band gap is much closer to experiments . Without any scissor operator being considered on electronic structure, it is found that the band gap present irregular decrease with increasing x .…”

Section: Resultssupporting

confidence: 85%

“…Comparing with previous calculated and experimental results, our theoretical band gap is much closer to experiments. 3,46 Without any scissor operator being considered on electronic structure, it is found that the band gap present irregular decrease with increasing x. The nonlinear behavior of band gap Table III.…”

Section: (2) Electronic Structures and Bondingmentioning

confidence: 99%

“…Spinel phase aluminum oxynitride (γ‐alon) is a solid solution located in the Al 2 O 3 ‐rich region in the AlN–Al 2 O 3 system . Owing to its excellent optical transparency (high transmittance in the wavelength range of 0.2–5.2 μm) and outstanding thermomechanical properties, fully dense alon ceramic can be used for a wide range of engineering applications .…”

Section: Introductionmentioning

confidence: 99%

“…S PINEL phase aluminum oxynitride (c-alon) is a solid solution located in the Al 2 O 3 -rich region in the AlN-Al 2 O 3 system. [1][2][3][4] Owing to its excellent optical transparency (high transmittance in the wavelength range of 0.2-5.2 lm) and outstanding thermomechanical properties, fully dense alon ceramic can be used for a wide range of engineering applications. 2,5,6 The high hardness and durability of c-alon make it suitable for use of missile domes, armor, and some commercial applications (such as lenses and point of sale scanner windows).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

First‐Principles Insight into the Composition‐Dependent Structure and Properties of γ‐Alon

Wang

Liu

et al. 2014

J. Am. Ceram. Soc.

View full text Add to dashboard Cite

Spinel type Aluminum oxynitride (γ‐alon) solid solution exists in the Al2O3‐rich region of AlN–Al2O3 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‐Al2O3 and the ideal Al3O3N with formula of Al(8+x)/3O4−xNx (0 ≤ x ≤ 1). The unit cell expands with increasing Al3O3N composition. The lattice parameter increases nonlinearly with the composition of Al3O3N, which deviates from Vegard's law. As x increases, the anions dilate from the AlIV 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 ε2(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.

show abstract

Section: Resultssupporting

confidence: 85%

Section: (2) Electronic Structures and Bondingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

First‐Principles Insight into the Composition‐Dependent Structure and Properties of γ‐Alon

Wang

Liu

et al. 2014

J. Am. Ceram. Soc.

View full text Add to dashboard Cite

show abstract

“…Three different structural models have been proposed to describe the disordered structure of γ–alon . The constant anion structural model (with the formula of Al (64 + x )/3 V Al[(8− x )/3] O 32− x N x , where 2 ≤ x ≤ 5) has been proven to be the most reasonable one by experiments and theoretical calculations . One to two aluminum vacancies are generated to keep the charge balance in the unit cell of γ–alon.…”

Section: Introductionmentioning

confidence: 99%

First‐Principles Study on Site Preference of Aluminum Vacancy and Nitrogen Atoms in γ–Alon

Wang

Liu

et al. 2013

J. Am. Ceram. Soc.

View full text Add to dashboard Cite

The disorder in c-alon is caused by random arrangement of nitrogen atoms and aluminum vacancies. To understand the properties and electronic structure of c-alon by theoretical methods, the most reasonable structure model is needed. We examined the site preference of nitrogen atoms and aluminum vacancies by first-principles density functional theory (DFT) calculations on Al 24 O 24 N 8 and Al 23 O 27 N 5 . The calculated results for Al 24 O 24 N 8 with the lowest total energy indicated that nitrogen atoms prefer to be far away from each other, rather than in a completely random arrangement. The further investigation on Al 23 O 27 N 5 shows that the aluminum vacancies tend to possess octahedral sites and coordinate only with oxygen atoms. Evaluated by lattice variances (D a and D h ) and simulated XRD pattern, the most reasonable structure model of Al 23 O 27 N 5 has little deviation from the experimental results. The calculated bulk modulus of 200.9 GPa in Al 23 O 27 N 5 is slightly lower than the experimental value. The electronic structure reveals that the bonds of Al-N and Al-O have partially covalent and ionic characterization, while the covalent bond strength of Al-N is stronger than that of Al-O. The calculated band gap is 3.99 eV, which is much closer to the experimental 4.56 eV than previous suggestions. W.-Y. Ching-contributing editor Manuscript No. 32185.

show abstract

From Diamond to Superhard Borides and Oxides

Lowther

2014

Comprehensive Hard Materials

View full text Add to dashboard Cite

Elastic constants of oxynitride aluminum spinel phases

Cited by 11 publications

References 26 publications

First‐Principles Insight into the Composition‐Dependent Structure and Properties of γ‐Alon

First‐Principles Insight into the Composition‐Dependent Structure and Properties of γ‐Alon

First‐Principles Study on Site Preference of Aluminum Vacancy and Nitrogen Atoms in γ–Alon

From Diamond to Superhard Borides and Oxides

Contact Info

Product

Resources

About