Japan Geoscience Union Meeting 2019

Presentation information

[E] Poster

P (Space and Planetary Sciences ) » P-CG Complex & General

[P-CG22] Shock responses of planetary materials elucidated from meteorites and dynamic compression experiments

Tue. May 28, 2019 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Toshimori Sekine(Center for High Pressure Science and Technology Advanced Research), Takuo Okuchi(Institute for Planetary Materials, Okayama University)

[PCG22-P08] First-principle study of the structural and electronic properties of N-doped MgAl2O4 spinel

*Chi Pui Tang1, Pak Kin Leong1, Toshimori Sekine2,3 (1.State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, 2.Center for High Pressure Science and Technology Advanced Research (HPSTAR) Shanghai Laboratory of HPSTAR, Shanghai, P.R. China, 3.Graduate School of Engineering, Osaka University)

Keywords:First principle calculation, Density functional theory, Spinel

On basis of the first principle calculation, we report a possible nitrogen doped structure of MgAl2O4 spinel. The structural and electronic properties (include the band structure, density of states and phonon) of spinel (MgAl2O4) and N-doped spinel (MgAl2O3.5N0.5) compounds are performed using density functional theory (DFT). The density and space group of two crystal cells are 3.47 g/cm3 (Fd3m) for MgAl2O4 and 3.38 g/cm3 (R3m) for MgAl2O3.5N0.5, respectively. The calculated direct band gaps at the Γ-point are about 5.13 eV for MgAl2O4 and 4.24 eV for MgAl2O3.5N0.5, respectively. The projected density of states (PDOS) shows that the tops of the valence bands are built up from ~93% of p(O) states and ~60% of p(N) + ~32% of p(O) states (for MgAl2O4 and MgAl2O3.5N0.5, respectively). In the phonon analysis, the lowest frequency of MgAl2O3.5N0.5 is redshifted to 36.6 cm-1 (MgAl2O4 is 39.8 cm-1) caused by the N-doped. We also calculate their cohesive energy in the pressure range of 0-150 GPa. We found that the cohesive energy of MgAl2O3.5N0.5 is lower than MgAl2O4 at the pressure higher than ~115 GPa, it implies that MgAl2O3.5N0.5 is more stable than MgAl2O4 at high pressure. Finally, we suggest that nitrogen atom would replace the oxygen of spinel in the depths of the earth. The results imply the deep mantle may storage a considerable amount of nitrogen.