NDLI: Lattice Dynamics Study of Phonon Instability and Thermal Properties of Type-I Clathrate K8Si46 under High Pressure

Content Provider	MDPI
Author	Zhang, Wei Zeng, Zhao Ge, Ni Li, Zhi
Abstract	For a further understanding of the phase transitions mechanism in type-I silicon clathrates K8Si46, ab initio self-consistent electronic calculations combined with linear-response method have been performed to investigate the vibrational properties of alkali metal K atoms encapsulated type-I silicon-clathrate under pressure within the framework of density functional perturbation theory. Our lattice dynamics simulation results showed that the pressure induced phase transition of K8Si46 was believed to be driven by the phonon instability of the calthrate lattice. Analysis of the evolution of the partial phonon density of state with pressure, a legible dynamic picture for both guest K atoms and host lattice, was given. In addition, based on phonon calculations and combined with quasi-harmonic approximation, the specific heat of K8Si46 was derived, which agreed very well with experimental results. Also, other important thermal properties including the thermal expansion coefficients and Grüneisen parameters of K8Si46 under different temperature and pressure were also predicted.
File Size	8197120
File Format	PDF
e-ISSN	19961944
DOI	10.3390/ma9080616
Journal	Materials
Issue Number	8
Volume Number	9
Language	English
Publisher Date	2016-07-25
Access Restriction	Open
Subject Keyword	phonon spectrum clathrate compounds lattice dynamics high pressure
Content Type	Text
Resource Type	Article

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Lattice Dynamics Study of Phonon Instability and Thermal Properties of Type-I Clathrate K8Si46 under High Pressure