Phonon Properties of Materials: Modeling and Experimentation: On-Demand Oral Presentations
Sponsored by: TMS Advanced Characterization, Testing, and Simulation Committee, TMS: Energy Conversion and Storage Committee
Program Organizers: Murali Gopal Muraleedharan, Oak Ridge National Laboratory; Zhe Cheng, University of Illinois at Urbana-Champaign; Kiarash Gordiz, Massachusetts Institute of Technology
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 10
Location: MS&T On Demand
Invited
Phonons and Twisting Symmetries in Non-symmorphic Materials: Lucas Lindsay1; 1Oak Ridge National Laboratory
Here I will discuss the role of structural twisting and symmetry in determining the vibrational behaviors of non-symmorphic materials and how these translate into spectral features and functionalities. We advance a ‘twist’ dynamical description of quasiparticles (e.g., phonons, Bloch electrons) in chiral and achiral crystals. This twisting description provides a fresh perspective on symmetry-enforced crossings, quasiparticle interactions, scattering observables, and band topologies. L.L. acknowledges support from the U. S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.
Invited
Transfer Learning for Phonon and Thermal Property Predictions: Zeyu Liu1; Tengfei Luo1; 1University of Notre Dame
Machine learning is trending to be an integral part of thermal science. In this talk, I will introduce our efforts in utilizing machine learning (ML) techniques to predict phonon properties and thermal modeling. I will talk about the use of a new ML method, called transfer learning, to establish accurate models based on limited data for predicting phonon and thermal transport properties, such as phonon frequency gap, heat capacity, speed of sound and lattice thermal conductivity.
Invited
High-temperature Heat Transport in Anharmonic Systems at the Nanoscale: Keivan Esfarjani1; 1University of Virginia
In this talk equilibrium and non-equilibrium formalisms to treat anharmonic systems at high temperatures are described.In equilibrium case, lattice dynamics at high-temperatures is described by an effective harmonic theory obtained from sampling of the phase space in the canonical ensemble. This could be done self-consistently based on a model anharmonic hamiltonian and is known as the self-consistent phonon theory. In the non-equilibrium case, while previous approaches used the Keldysh formalism, we have derived a simpler classical formalism based on the equation of motion method and Langevin thermostats attached to the central anharmonic device. In contrast to previous results, we find that the leading term which needs to be included is the quartic anharmonic term. Cubic terms are then a second-order correction to the latter, which can either be added perturbatively or self-consistently.Finally, our approach leads to a current-conserving approximation, which is not always guaranteed in non-linear models.
Experimental and Computational Thermal Conductivity Reduction in Single Crystal Thorium Dioxide from Lattice Defects: Cody Dennett1; Marat Khafizov2; Anter El-Azab3; David Hurley1; 1Idaho National Laboratory; 2Ohio State University; 3Purdue University
Actinide and lanthanide fluorite oxides form an important class of ceramic energy materials with applications ranging from nuclear fuels to solid oxide fuel cells. Potential application environments for ThO2 in particular include high radiation fields which directly generate lattice defects. Such defects drastically influence phonon thermal transport, a controlling safety and performance property. Here, we use a combination of ion beam irradiation and spatial domain thermoreflectance measurements to generate a defected region in single crystal ThO2 specimens in a variety of conditions and measure the resulting thermal conductivity from 77-300K. In parallel, defect evolution models are used with the linearized Boltzmann transport equation (BTE) and computed defect scattering cross sections to directly return lattice thermal conductivity over the same temperature range. The agreement shown between modeling and experiment is the first step towards a predictive thermal transport capability in fluorite oxides across a wide range of environmental conditions.
Tailoring Thermal Transport in Insulators Using Energetic Ions: Vinay Chauhan1; Joshua Ferrigno1; Saqeeb Adnan1; Zhandos Utegulov2; Cody Dennett3; Amey Khanolkar3; Zilong Hua3; Lingfeng He3; David Hurley3; Marat Khafizov1; 1Ohio State University; 2Nazarbayev University; 3Idaho National Laboratory
Ion implantation and nuclear transmutation are established methods for tailoring electronic properties of semiconductors. In this presentation, we discuss use of ion beam modification to change phonon mediated thermal transport characteristics of insulating materials. Modulated thermorefleactance methods are used to measure conductivity of the modified regions, whereas transmission electron microscopy is employed to characterize microstructure. Implantation of xenon swift heavy ions accelerated to several tens of MeV into sapphire introduced an aligned array of ion tracks. These aligned nano-channels induce thermal anisotropy within the ion impacted region, which is attributed to directional scattering of phonons with ion tracks and phonon confinement effects. Irradiations of fluorite oxides such cerium and thorium dioxide with few MeV protons at elevated temperatures resulted in formation of dislocation loops. Careful analysis of thermal conductivity reduction under these implantation conditions suggests a very strong phonon scattering by the faulted loops owing to their long-range strain field.
Understanding Ionic Conduction Mechanisms in Glassy Electrolytes Using MD Vibrational Analysis: Cameran Beg1; John Kieffer1; 1University of Michigan
MD simulations allow one to observe the behavior of all atoms involved in the ionic transport process to elucidate the underlying mechanisms. At Tg and below, cation jumps between adjacent sites are a rare event, invalidating standard measures, such as the mean squared displacements, for the evaluation of cation mobility. We explore an approach for estimating cation mobility based on the analysis of deviatory modes of motion captured by the velocity autocorrelation function, the integral of which yields the diffusion coefficient. A non-zero diffusion coefficient is the consequence of damping of the velocity correlation function. By deconstructing the velocity correlation function and it’s Fourier transform pair via a variant of Prony’s analysis, we establish a working connection between cation mobility and the glass network’s phonon modes toward the development of a materials design criteria for solid-state electrolytes. (Acknowledgement: NSF-DMR 1610742.)