TY - JOUR
T1 - "Phonon Dynamics in Type-VIII Silicon Clathrates: Beyond the Rattler Concept"
AU - Norouzzadeh, Payam
AU - Myles, Charles
AU - Vashaee, Daryoosh
PY - 2017/5/11
Y1 - 2017/5/11
N2 - Clathrates can form a type of guest-host solid structures that, unlike most crystalline solids, have very low thermal conductivity. It is generally thought that the guest atoms caged inside the host framework act as “rattlers” and induce lattice dynamics disorders responsible for the small thermal conductivity.We performed a systematic
study of the lattice dynamical properties of type-VIII clathrates with alkali and alkaline-earth guests, i.e., X8Si46
(X = Na, K, Rb, Cs, Ca, Sr, and Ba). The energy dependent participation ratio (PR) and the atomic participation
ratio of phonon modes extracted from density functional theory calculations revealed that the rattler concept
is not adequate to describe the effect of fillers as they manifest strong hybridization with the framework. For
the case of heavy fillers, such as Rb, Sr, Cs, and Ba, a phonon band gap was formed between the acoustic and
optical branches. The calculated PR indicated that the fillers suppress the acoustic phonon modes an
AB - Clathrates can form a type of guest-host solid structures that, unlike most crystalline solids, have very low thermal conductivity. It is generally thought that the guest atoms caged inside the host framework act as “rattlers” and induce lattice dynamics disorders responsible for the small thermal conductivity.We performed a systematic
study of the lattice dynamical properties of type-VIII clathrates with alkali and alkaline-earth guests, i.e., X8Si46
(X = Na, K, Rb, Cs, Ca, Sr, and Ba). The energy dependent participation ratio (PR) and the atomic participation
ratio of phonon modes extracted from density functional theory calculations revealed that the rattler concept
is not adequate to describe the effect of fillers as they manifest strong hybridization with the framework. For
the case of heavy fillers, such as Rb, Sr, Cs, and Ba, a phonon band gap was formed between the acoustic and
optical branches. The calculated PR indicated that the fillers suppress the acoustic phonon modes an
U2 - 10.1103/PhysRevB.95.195206
DO - 10.1103/PhysRevB.95.195206
M3 - Article
SP - 195206-1 to 195206-9
JO - Physical Review B
JF - Physical Review B
ER -