论文标题
在隔分子 - 原子层$ \ mathrm {msi_2n_4} $（m = mo和w）中的内在压电对内在的压电的结构效果
Structure effect on intrinsic piezoelectricity in septuple-atomic-layer $\mathrm{MSi_2N_4}$ (M=Mo and W)
论文作者
论文摘要
最近实验合成的单层$ \ MATHRM {MOSI_2N_4} $和$ \ MATHRM {WSI_2N_4} $（\ TextColor [RGB] {0.00,0.00,00,1.00}在这项工作中，基于从头算的计算，我们报告了对隔离 - 原子 - 原子级$ \ mathrm {msi_2n_4} $（m = mo和w）中内在的压电的影响（$α_i$（$α_i$（$ i = 1 $ = 1至6））。 （m = mo和w）$α_i$（$ i $ = 1至6）都是间接的频段间隙半导体。计算结果表明，$ \ MATHRM {MOSI_2N_4} $和$ \ MATHRM {WSI_2N_4} $单层对压电和压力系数的结构依赖性相同（$ d_ {11}}} $ e_ {11} $ e_ {11} $），以及$ nirosic and odiTion $ ecodition，$ e_ nirosic和$ e。单层$ \ MATHRM {MA_2Z_4} $（M = Cr，Mo和W; A = Si and Ge; Z = N和P）的固有的压电电源具有$α_1$和$α_2$ eptas $ and shems $ and shouts neminecipies，因为它们是$α_1$和$α_2$ $α_2$阶段非常接近。最重要的结果是单层$ \ mathrm {ma_2z_4} $含有P原子的压电极化比在内的压电极化更强。 $ \ mathrm中最大的$ d_ {11} $ {ma_2n_4} $材料是1.85 pm/v，接近最小的$ d_ {11} $ 1.65 pm/v in $ \ mathrm {ma_2p_4} $ monolayers。对于$ \ mathrm {ma_2p_4} $，最大的$ d_ {11} $最多为6.12 pm/v。在22个单层中，$α_1$ - $ \ MATHRM {CRSI_2P_4} $，$α_1$ - $ \ MATHRM {MOSI_2P_4} $，$α_1$ - $ \ $ \ MATHRM $α_2$ - $ \ MATHRM {CRGE_2P_4} $具有大$ d_ {11} $，它大于或接近或接近5 pm/v，这是散装压电材料的典型值。
The recently experimentally synthesized monolayer $\mathrm{MoSi_2N_4}$ and $\mathrm{WSi_2N_4}$ (\textcolor[rgb]{0.00,0.00,1.00}{Science 369, 670-674 (2020})) lack inversion symmetry, which allows them to become piezoelectric. In this work, based on ab initio calculations, we report structure effect on intrinsic piezoelectricity in septuple-atomic-layer $\mathrm{MSi_2N_4}$ (M=Mo and W), and six structures ($α_i$ ($i$=1 to 6)) are considered with the same space group.It is found that $\mathrm{MSi_2N_4}$ (M=Mo and W) with $α_i$ ($i$=1 to 6) all are indirect band gap semiconductors. Calculated results show that $\mathrm{MoSi_2N_4}$ and $\mathrm{WSi_2N_4}$ monolayers have the same structural dependence on piezoelectric strain and stress coefficients ($d_{11}$ and $e_{11}$), together with the ionic and electronic contributions to $e_{11}$.Finally, we investigate the intrinsic piezoelectricity of monolayer $\mathrm{MA_2Z_4}$ (M=Cr, Mo and W; A=Si and Ge; Z=N and P) with $α_1$ and $α_2$ phases expect $\mathrm{CrGe_2N_4}$, because they all are semiconductors and their enthalpies of formation between $α_1$ and $α_2$ phases are very close. The most important result is that monolayer $\mathrm{MA_2Z_4}$ containing P atom have more stronger piezoelectric polarization than one including N atom. The largest $d_{11}$ among $\mathrm{MA_2N_4}$ materials is 1.85 pm/V, which is close to the smallest $d_{11}$ of 1.65 pm/V in $\mathrm{MA_2P_4}$ monolayers. For $\mathrm{MA_2P_4}$, the largest $d_{11}$ is up to 6.12 pm/V. Among the 22 monolayers, $α_1$-$\mathrm{CrSi_2P_4}$, $α_1$-$\mathrm{MoSi_2P_4}$, $α_1$-$\mathrm{CrGe_2P_4}$, $α_1$-$\mathrm{MoGe_2P_4}$ and $α_2$-$\mathrm{CrGe_2P_4}$ have large $d_{11}$, which are greater than or close to 5 pm/V, a typical value for bulk piezoelectric materials.
