Electronic structures and phase transition characters of β-, P61-, P62- and 8-Si3N4 under extreme conditions： a density functional theory study

This paper describes the results of structural, electronic and elastic properties of silicon nitride （in its high-pressure P61 and P62 phases） through the first-principles calculation combined with an ultra-soft pseudo- potential. The computed equilibrium lattice constants agree well with the experi...

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Bibliographic Details
Published in半导体学报：英文版 no. 2; pp. 24 - 28
Main Author 陈东 仓玉萍 罗永松
Format Journal Article
LanguageEnglish
Published 2015
Subjects
字符
密度泛函理论
平衡晶格常数
极端条件
氮化硅
电子结构
相变
第一原理计算
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ISSN1674-4926

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Summary:This paper describes the results of structural, electronic and elastic properties of silicon nitride （in its high-pressure P61 and P62 phases） through the first-principles calculation combined with an ultra-soft pseudo- potential. The computed equilibrium lattice constants agree well with the experimental data and the theoretical results. The strongest chemical bond （N-Si bond） shows a covalent nature with a little weaker ionic character. P61- Si3N4 is more stable than P62-Si3N4 due mainly to the fact that the shorter N-Si bond in the P61 phase allows stronger electron hybridizations. We have also predicted the phase stability of Si3N4 using the quasi-harmonic approximation, in which the lattice vibration and phonon effect are both considered. The results show that the 13 P61 phase transition is very likely to occur at 42.9 GPa and 300 K. The reason why the β→P61→3 phase transitions had never been observed is also discussed.
Bibliography:phase transition; bond lengths; elastic constants; density functional theory
This paper describes the results of structural, electronic and elastic properties of silicon nitride （in its high-pressure P61 and P62 phases） through the first-principles calculation combined with an ultra-soft pseudo- potential. The computed equilibrium lattice constants agree well with the experimental data and the theoretical results. The strongest chemical bond （N-Si bond） shows a covalent nature with a little weaker ionic character. P61- Si3N4 is more stable than P62-Si3N4 due mainly to the fact that the shorter N-Si bond in the P61 phase allows stronger electron hybridizations. We have also predicted the phase stability of Si3N4 using the quasi-harmonic approximation, in which the lattice vibration and phonon effect are both considered. The results show that the 13 P61 phase transition is very likely to occur at 42.9 GPa and 300 K. The reason why the β→P61→3 phase transitions had never been observed is also discussed.
11-5781/TN
ISSN:1674-4926