Mechanical Properties of Intermetallic Clathrates

Matthias Falmbigl, Stephan Puchegger, Peter Franz Rogl

The present work provides a comprehensive compilation and discussion

covering hardness, experimentally determined elastic properties, thermal expan-

sion, and Debye and Einstein temperatures for intermetallic clathrates. Comparing

hardness values and elastic properties a major influence of the framework atoms is

observed. Hardness and elastic moduli change linearly with the Si/Ge-ratio. Also a

linear temperature dependence of the elastic properties is observed. In the case that

vacancies are present in the clathrate framework, the hardness of different com-

pounds decreases almost linearly with an increasing vacancy-content. As Debye

and Einstein temperatures are of significance for the vibrational spectra and per-

formance of thermoelectric materials, corresponding values extracted from various

measurement techniques such as thermal expansion, sound velocity, specific heat,

electrical resistivity or X-ray absorption and diffraction measurements are evalu-

ated. The Debye temperatures correlate with the melting temperatures of the

intermetallic clathrates, and the Einstein temperatures for similar guest atoms

show a linear dependence on the cage size. Wherever available, experimental data

are compared with those from DFT model simulations. In general the experi-

mentally derived values match those theoretically calculated

Institut für Physikalische Chemie, Fakultätszentrum für Nanostrukturforschung
ÖFOS 2012
104017 Physikalische Chemie, 104011 Materialchemie
Link zum Portal