Temperature dependent structural properties and bending rigidity of pristine and defective hexagonal boron nitride
Temperature dependent structural properties and bending rigidity of pristine and defective hexagonal boron nitride
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DOI：
10.1088/0953-8984/27/31/315302
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发表时间：
2015-08-12
影响因子：
2.7
通讯作者：
Valsakumar, M. C.
中科院分区：
文献类型：
--
作者：
Thomas, Siby;Ajith, K. M.;Valsakumar, M. C.
通过使用经调整的Tersoff型原子间经验势进行原子模拟，在较宽的温度范围内研究了单层原始和有缺陷的氮化硼片（h - BN）的结构和热力学性质。研究了原始以及有缺陷的h - BN片的晶格参数、径向分布函数、定容比热、线性热膨胀系数以及热激发波纹的高度相关函数随温度的变化。比热在高温下显著超过杜隆 - 珀蒂极限，这被解释为h - BN中存在强非谐性的标志。对高度涨落< h(2)>的分析表明，弯曲刚度和高度涨落的方差强烈依赖于温度，并且使用膜的连续介质理论对此进行了解释。对高度 - 高度相关函数的详细研究表明，由于h - BN中的强非谐性，其偏离了膜的谐性理论的预测。还可以看到，高度涨落的方差随着缺陷浓度的增加而增大。
Structural and thermodynamical properties of monolayer pristine and defective boron nitride sheets (h-BN) have been investigated in a wide temperature range by carrying out atomistic simulations using a tuned Tersoff-type inter-atomic empirical potential. The temperature dependence of lattice parameter, radial distribution function, specific heat at constant volume, linear thermal expansion coefficient and the height correlation function of the thermally excited ripples on pristine as well as defective h-BN sheet have been investigated. Specific heat shows considerable increase beyond the Dulong-Petit limit at high temperatures, which is interpreted as a signature of strong anharmonicity present in h-BN. Analysis of the height fluctuations, < h(2)>, shows that the bending rigidity and variance of height fluctuations are strongly temperature dependent and this is explained using the continuum theory of membranes. A detailed study of the height-height correlation function shows deviation from the prediction of harmonic theory of membranes as a consequence of the strong anharmonicity in h-BN. It is also seen that the variance of the height fluctuations increases with defect concentration.