Using the first-principles calculations and combining with the phonon Boltzmann transport equation, we systematically investigated the phonon thermal transport properties of II–VI group graphenelike materials (BeO, MgO, CaO, SrS, and SrSe). The lattice thermal conductivities ${\kappa }_L$’s of 118.68, 42.48, 11.13, 3.33, and 3.09 W/mK are obtained at 300 K in BeO, MgO, CaO, SrS, and SrSe, respectively, which is much lower than that of graphene. Strikingly, the ${\kappa }_L$ of SrS and SrSe is lower than most two-dimensional materials. Further analyses revealed that (i) the lower phonon group velocity of SrS and SrSe caused by a larger atomic mass reduces the ${\kappa }_L$ and (ii) strong anharmonicity and more available phonon scattering channels enhance phonon anharmonic scattering, resulting in lower ${\kappa }_L$. By means of the relationship between ${\kappa }_L$ and the phonon mean-free path and the width of nanowires, the size dependence of lattice thermal conductivity is investigated as well, which provides a theoretical basis for the design of thermoelectric nanostructures.

中文翻译：

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II-VI类石墨烯类材料中声子热输运的第一性原理研究

使用第一性原理计算并结合声子玻尔兹曼输运方程，我们系统地研究了II–VI类石墨烯类材料（BeO，MgO，CaO，SrS和SrSe）的声子热输运性质。晶格热导率${\kappa }_{\mathrm{大号}}$在300 K的BeO，MgO，CaO，SrS和SrSe中，在300 K时分别获得118.68、42.48、11.13、3.33和3.09 W / mK的值，这远低于石墨烯。惊人的是${\kappa }_{\mathrm{大号}}$SrS和SrSe的比值低于大多数二维材料。进一步的分析表明（i）较大的原子量引起的SrS和SrSe声子基团速度降低，${\kappa }_{\mathrm{大号}}$ （ii）强非谐性和更多可用的声子散射通道增强了声子非谐散射，从而降低了声子 ${\kappa }_{\mathrm{大号}}$。通过之间的关系${\kappa }_{\mathrm{大号}}$ 并研究了声子的平均自由程和纳米线的宽度，研究了晶格热导率的大小依赖性，为热电纳米结构的设计提供了理论依据。