5-1 内包原子種がシリコンクラスレート格子熱伝導率に及ぼす影響 : 古典分子動力学法による検討(セッション5:OS1-2 マルチスケール・シミュレーションとナノ計測)

Abstract

In this study, effects of contained guest atomic species in Si clathrates on the lattice thermal conductivity were studied by using classical molecular dynamics calculations. Their lattice thermal conductivities were calculated from heat current obtained in the calculations, which was called as the Green-Kubo method. As a result, lattice thermal conductivities of type-I Si clathrates, Si_<46>M_8 (M=Na, K, Rb, Cs, Be, Mg, Sr, and Ba), were obtained. The obtained lattice thermal conductivity could be considered as a function of characteristic frequency 1/2(k/m)^<1/2>, where m and k indicate atomic weight of a guest atom and a force constant felt by a guest atom in a Si cage, respectively. Lattice thermal conductivity increases as the characteristic frequency increases in frequency range more than 3THz, even if the atomic weight was artificially changed. On the other hand, in frequency range less than 3THz, lattice thermal conductivity decreases as characteristic frequency increases.