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Full-Text Articles in Engineering
Effect Of Disorder On The Thermal Transport And Elastic Properties In Thermoelectric Zn4Sb3, S. Bhattacharya, R.P. Hermann, Veerle Keppens, T. M. Tritt, G. J. Snyder
Effect Of Disorder On The Thermal Transport And Elastic Properties In Thermoelectric Zn4Sb3, S. Bhattacharya, R.P. Hermann, Veerle Keppens, T. M. Tritt, G. J. Snyder
Faculty Publications and Other Works -- Materials Science & Engineering
Zn4Sb3 undergoes a phase transition from α to β phase at T1≈250 K. The high temperature β-Zn4Sb3 phase has been widely investigated as a potential state-of-the-art thermoelectric (TE) material, due to its remarkably low thermal conductivity. We have performed electronic and thermal transport measurements exploring the structural phase transition at 250 K. The α to β phase transition manifests itself by anomalies in the resistivity, thermopower, and specific heat at 250 K as well as by a reduction in the thermal conductivity as Zn4Sb3 changes phase from the ordered …
Direct Experimental Evidence For Atomic Tunneling Of Europium In Crystalline Eu8Ga16Ge30, Raphaël P. Hermann, Veerle Keppens, Pierre Bonville, George S. Nolas, Fernande Grandjean, Gary J. Long, Hans M. Christen, Bryan C. Chakoumakos, Brian C. Sales, David Mandrus
Direct Experimental Evidence For Atomic Tunneling Of Europium In Crystalline Eu8Ga16Ge30, Raphaël P. Hermann, Veerle Keppens, Pierre Bonville, George S. Nolas, Fernande Grandjean, Gary J. Long, Hans M. Christen, Bryan C. Chakoumakos, Brian C. Sales, David Mandrus
Faculty Publications and Other Works -- Materials Science & Engineering
Mössbauer-effect and microwave absorption experimental evidence unambiguously demonstrates the presence of slow, ∼450 MHz, tunneling of magnetic europium between four equivalent sites in Eu8Ga16Ge30, a stoichiometric clathrate. Remarkably, six of the eight europium atoms, or 11% of the constituents in this solid, tunnel between these four sites separated by 0.55 Å. The off centering of the atoms or ions in crystalline clathrates appears to be a promising route for producing Rabi oscillators in solid-state materials.
Magnetic And Electronic Properties Of Eu4Sr4Ga16Ge30, G.T. Woods, J. Martin, M. Beekman, Raphaël P. Hermann, Fernande Grandjean, Veerle Keppens, O. Leupold, Gary J. Long, G.S. Nolas
Magnetic And Electronic Properties Of Eu4Sr4Ga16Ge30, G.T. Woods, J. Martin, M. Beekman, Raphaël P. Hermann, Fernande Grandjean, Veerle Keppens, O. Leupold, Gary J. Long, G.S. Nolas
Faculty Publications and Other Works -- Materials Science & Engineering
Magnetization, static and ac magnetic susceptibility, nuclear forward scattering, and electrical resistivity measurements have been performed on polycrystalline Eu4Sr4Ga16Ge30, a type I clathrate that has divalent strontium and europium ions encapsulated within a Ga-Ge framework. These data are compared with those of type I clathrates Eu8Ga16Ge30 and Eu6Sr2Ga16Ge30. The ferromagnetic ordering of these Eu-containing clathrates is substantially altered by the incorporation of strontium, as compared to Eu8Ga16Ge30. Ferromagnetism, accompanied by a relatively large …