论文标题
静液压压力对孤对活动和bi $ _2 $ o $ $ _2 $ s中的孤对运输的影响
Effect of Hydrostatic Pressure on Lone Pair Activity and Phonon Transport in Bi$_2$O$_2$S
论文作者
论文摘要
Dibismuth Dioxychalcogenides，Bi $ _2 $ o $ _2 $ CH（CH = S，SE，TE）是新兴的下一代电子产品和热电话的材料类，具有超高载波机动性和出色的空气稳定性。其中，Bi $ _2 $ o $ _2 $ s由于立体化活性6 $ S^2 $单对BI $^{3+} $ cation，异质结合和组成元素的高质量对比度而引人入胜。在这项工作中，我们系统地研究了静液压压力及其对BI $ _2 $ o $ o $ _2 $ s的晶格动力和声子传输属性的影响，通过使用第一原理计算以及Boltzmann运输理论。环境$ pnmn $阶段表现出300 k处的1.71 w-m/k的平均晶格导热率（$κ__l$）为1.71 w-m/k。我们还发现，bi $ _2 $ _2 $ o $ _2 $ s进行了从低对称性（$ pnmn $）到高symmetry（$ i4/mmm $ $ i4/mmmmmmmmm）的结构性相过渡，从居中。压缩后，Bi $^{3+} $阳离子的唯一对活动被抑制，这将$κ_l$在5 GPA时以$ i4/mmm $ apeas的速度在5 GPA时增加到4.92 w-m/k。计算出的声子寿命和grüneisen参数表明，由于进一步抑制孤对，加强内部和分子间相互作用，非谐度会随着压力的增加而降低，这将平均室温$κ_L$ $κ_L$至12.82 w-m/k在20 GPA时。总体而言，本研究对BI $^{3+} $ cation lone Pai的立体化学活动及其对BI $ $ _2 $ o $ $ _2 $ s的声子传输属性的后果进行了全面了解对BI $^{3+}的立体化学活动的影响。
Dibismuth dioxychalcogenides, Bi$_2$O$_2$Ch (Ch = S, Se, Te) are emerging class of materials for next generation electronics and thermoelectrics with an ultrahigh carrier mobility and excellent air stability. Among these, Bi$_2$O$_2$S is fascinating because of stereochemically active 6$s^2$ lone pair of Bi$^{3+}$ cation, heterogeneous bonding and high mass contrast of constituent elements. In this work, we systematically investigate the effect of hydrostatic pressure and its implications on lattice dynamics and phonon transport properties of Bi$_2$O$_2$S by employing first principles calculations along with the Boltzmann transport theory. The ambient $Pnmn$ phase exhibits a low average lattice thermal conductivity ($κ_l$) of 1.71 W-m/K at 300 K. We also find that Bi$_2$O$_2$S undergoes a structural phase transition from low symmetry ($Pnmn$) to a high symmetry ($I4/mmm$) structure around 4 GPa due to the Bi$^{3+}$ cation centering. Upon compression the lone pair activity of Bi$^{3+}$ cation is suppressed, which increases $κ_l$ by nearly 3 times to 4.92 W-m/K at 5 GPa for $I4/mmm$ phase. The calculated phonon lifetimes and Grüneisen parameters show that anharmonicity reduces with increasing pressure due to further suppression of lone pair, strengthening of intra and inter molecular interactions, which raises the average room temperature $κ_l$ to 12.82 W-m/K at 20 GPa. Overall, the present study provides a comprehensive understanding of hydrostatic pressure effects on stereochemical activity of the Bi$^{3+}$ cation lone pair and its consequences on phonon transport properties of Bi$_2$O$_2$S.
