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Structure, thermal, and transport properties of the clathrates Sr8Zn8Ge38, Sr8Ga16Ge30, and Ba8Ga16Si30

dc.contributor.authorQiu, LYen_US
dc.contributor.authorSwainson, IPen_US
dc.contributor.authorNolas, GSen_US
dc.contributor.authorWhite, MAen_US
dc.date.accessioned2013-08-23T15:58:42Z
dc.date.available2013-08-23T15:58:42Z
dc.date.issued2004-07en_US
dc.description.abstractThe structural parameters, thermal properties, and transport properties of three type I clathrates, namely Sr8Zn8Ge38, Sr8Ga16Ge30, and Ba8Ga16Si30, have been determined at or below room temperature. The structural parameters of these clathrates were determined by powder neutron diffraction. Their lattice thermal expansion is two to four times greater than that of the diamond phases of silicon and germanium, consistent with more anharmonic lattice vibrations. From the temperature dependence of the isotropic atomic displacement parameters, the estimated rattling frequencies of guests in the large cages of these clathrates are in the range 50-60 cm(-1). The heat capacities of these three clathrate materials increase smoothly with increasing temperatures and approach the Dulong-Petit value around room temperature. The Gruneisen parameter of these materials is constant between 100 and 300 K but increases below 100 K, due to the dominance of the low-frequency guest-rattling modes. The room-temperature electrical resistivity and the Seebeck coefficient show that these materials are metallic. The temperature profile of the thermal conductivities and calculated phonon mean free paths of these materials show glasslike behavior, although they are crystalline materials, indicating strong resonant scattering of heat-carrying acoustic phonons via the rattling of the guests in the clathrate cages.en_US
dc.identifier.citationQiu, LY, IP Swainson, GS Nolas, and MA White. 2004. "Structure, thermal, and transport properties of the clathrates Sr8Zn8Ge38, Sr8Ga16Ge30, and Ba8Ga16Si30." Physical Review B 70(3): 035208-035208. Copyright © 2004 American Physical Society.en_US
dc.identifier.issn1098-0121en_US
dc.identifier.issue3en_US
dc.identifier.startpage035208en_US
dc.identifier.urihttp://dx.doi.org/10.1103/PhysRevB.70.035208en_US
dc.identifier.urihttp://hdl.handle.net/10222/36203
dc.identifier.volume70en_US
dc.relation.ispartofPhysical Review Ben_US
dc.titleStructure, thermal, and transport properties of the clathrates Sr8Zn8Ge38, Sr8Ga16Ge30, and Ba8Ga16Si30en_US
dc.typearticleen_US

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