Modeling non-harmonic behavior of materials from experimental inelastic neutron scattering and thermal expansion measurements.
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2016-09-28
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Abstract
Based on thermodynamic principles, we derive expressions quantifying the non-harmonic vibrational behavior of materials, which are rigorous yet easily evaluated from experimentally available data for the thermal expansion coefficient and the phonon density of states. These experimentally-derived quantities are valuable to benchmark first-principles theoretical predictions of harmonic and non-harmonic thermal behaviors using perturbation theory, ab initio molecular-dynamics, or Monte-Carlo simulations. We illustrate this analysis by computing the harmonic, dilational, and anharmonic contributions to the entropy, internal energy, and free energy of elemental aluminum and the ordered compound [Formula: see text] over a wide range of temperature. Results agree well with previous data in the literature and provide an efficient approach to estimate anharmonic effects in materials.
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Bansal, Dipanshu, Amjad Aref, Gary Dargush and Olivier Delaire (2016). Modeling non-harmonic behavior of materials from experimental inelastic neutron scattering and thermal expansion measurements. J Phys Condens Matter, 28(38). p. 385201. 10.1088/0953-8984/28/38/385201 Retrieved from https://hdl.handle.net/10161/11987.
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Scholars@Duke
Olivier Delaire
The Delaire group investigates atomistic transport processes of energy and charge, and thermodynamics in energy materials. We use a combined experimental and computational approach to understand and control microscopic energy transport for the design of next-generation materials, in particular for sustainable energy applications. Current materials of interest include superionic conductors, photovoltaics, thermoelectrics, ferroelectrics/multiferroics, and metal-insulator transitions. Our group's studies provide fundamental insights into atomic dynamics and elementary excitations in condensed-matter systems (phonons, electrons, spins), their couplings and their effects on macroscopic properties. We probe the microscopic underpinnings of transport and thermodynamics properties by integrating neutron and x-ray scattering, optical spectroscopy, and thermal characterization, together with quantum-mechanical computer simulations.
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