Theoretical study on elastic properties of Si2N2O by ab initio calculation
Theoretical study on elastic properties of Si2N2O by ab initio calculation
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从头计算Si2N2O弹性性质的理论研究
DOI：
10.7567/jjap.57.07lb04
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
H. Ogi
中科院分区：
文献类型：
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作者：
Seiya Tsuboi;Kanta Adachi;A. Nagakubo;H. Ogi
结晶Si2N2O的弹性常数自20世纪60年代被发现以来一直是未知的。用从头计算方法确定了正交晶系Si_2N_2O的9个独立弹性常数。我们对一个单胞施加了应变达± 0.01的各种变形模式，计算了能量-应变关系，并通过谐波振荡函数拟合得到了所有的弹性常数。我们的结果如下：C11 = 311.1，C22 = 238.5，C33 = 317.9，C44 = 136.1，C55 = 57.6，C66 = 73.9，C12 = 79.6，C13 = 52.2，C23 = 33.6 GPa。尽管晶体结构和对称性不同，但Si2N2O的方向超平均杨氏模量很好地解释了α-SiO2和β-Si3N4的氮含量和杨氏模量。研究了声波速度的各向异性，并根据晶体结构研究了其起源。确定了行波传播的准各向同性平面。
The elastic constants of crystalline Si2N2O remain unknown since it was discovered in the 1960s. We determine the nine independent elastic constants of orthorhombic Si2N2O by ab initio calculations. We applied various deformation modes with strains up to ±0.01 to a unit cell, calculated the energy-strain relationships, and deduced all the elastic constants by fitting the harmonic-oscillation function. Our results are as follows: C11 = 311.1, C22 = 238.5, C33 = 317.9, C44 = 136.1, C55 = 57.6, C66 = 73.9, C12 = 79.6, C13 = 52.2, and C23 = 33.6 GPa. Despite the different crystal structures and symmetries, the direction-over-averaged Young’s modulus of Si2N2O is well explained by the nitrogen content and Young’s moduli of α-SiO2 and β-Si3N4. The anisotropy of sound-wave velocity was investigated, and its origin was examined on the basis of the crystallographic structure. The quasi-isotropic plane for the longitudinal-wave propagation was identified.