Thermal Property Characterization, Modeling, and Theory in Extreme Environments: Early Career Scholars in Thermal Properties
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee
Program Organizers: Janelle Wharry, Purdue University; Mukesh Bachhav, Idaho National Laboratory; Marat Khafizov, Ohio State University; Eric Lass, University of Tennessee-Knoxville; Vikas Tomar, Purdue University; Tiankai Yao, Idaho National Laboratory; Cody Dennett, Commonwealth Fusion Systems; Karim Ahmed, Texas A&M University
Wednesday 8:30 AM
March 17, 2021
Room: RM 53
Location: TMS2021 Virtual
Session Chair: Cody Dennett, Idaho National Laboratory; Fergany Badry, Texas A&M University
8:30 AM Invited
A Thermodynamically-consistent Model for Heat Transport in Heterogeneous Solids: Karim Ahmed1; Fergany Badry1; 1Texas A&M University
A novel model for heat conduction in heterogeneous solids was developed based on the thin-interface description of interfaces. In contrast to existing models, our new model treats an interface as an autonomous “phase” with its own thermal conductivity. The Kapitza resistance/conductance of a thin interface is then derived in terms of the interface thermal conductivity and width. This treatment allows the model to simulate the change of Kapitza resistance/conductance with segregation/doping, interface structure/phase transition, or interface decohesion. Additionally, it is shown that when non-local effects are included in Fourier’s law, the size dependent conductivity and thermal rectification phenomena can be explained in a unified manner. Moreover, since the model assumes a finite width for interfaces, it is expected to give better predictions than its sharp-interface-based counterparts for nanocrystalline solids. High-fidelity finite-element simulations were conducted to validate the predictions of the new model and proved its higher accuracy.
8:55 AM Invited
Defect Density and Annealing Kinetics Estimation Using Thermal Diffusivity Measurements from Transient Grating Spectroscopy: Mohamed Abdallah Reza1; Hongbing Yu1; Kenichiro Mizohata2; Felix Hofmann1; 1University Of Oxford; 2University of Helsinki
Irradiation damage significantly changes the properties of tungsten, the main candidate material for fusion reactor armor. Using transient grating spectroscopy (TGS) we study the reduction of thermal diffusivity in self-ion implanted tungsten from 0.0001 to 10 dpa. A kinetic theory (KT) model is used to estimate the irradiation-induced point defect density from the measured thermal diffusivity data. This is compared to prior molecular dynamics (MD) simulations and TEM observations of ion-irradiation-induced defects in tungsten. Since we have proven the capability of TGS with the KT model in providing defect density estimates on room temperature samples, this is extended to samples that are annealed in-situ. This is possible due to the invariance of the TGS method with respect to sample temperature and implemented using a TGS setup with in-situ heating up to 800 C. Hence, annealing kinetics of the irradiation induced defect populations are studied utilizing TGS with in-situ heating capabilities.
9:20 AM Invited
Thermal Behaviors of Correlated Insulators ThO2 and SmB6: Narayan Poudel1; Daniel Murray1; Matthew Mann2; Jason Jeffries3; Krzysztof Gofryk1; 1Idaho National Laboratory; 2Air Force Research Laboratory; 3Lawrence Livermore National Laboratory
Thermal transport properties of single crystals are essential in design and development of modern nuclear reactors. These properties also play important role in probing the new quantum materials. In this work, we present our detailed study of thermal transport in thorium dioxide (ThO2) and samarium hexaboride (SmB6) single crystals. Both materials crystalize in the cubic crystal structure and their properties are governed by strong electronic correlations. ThO2 is a wide-gap transparent insulator (Eg~5-6 eV) whereas SmB6 is a narrow-gap topological Kondo insulator (Eg<15 meV). By performing extensive thermal studies at low temperatures, where different scattering mechanisms such as boundary, defects, and/or phonon-phonon dominate heat transport, we are able to study details of phonon-phonon interactions in ThO2 and the effects of boundary scattering in micro-size SmB6 single crystal.
9:45 AM Invited
Thermal Conductivity Degradation from Irradiation-induced Microstructural Defects in Single Crystal Thorium Dioxide: Amey Khanolkar1; Zilong Hua1; Cody Dennett1; Marat Khafizov2; Tiankai Yao1; Kaustubh Bawane1; Lingfeng He1; J. Matthew Mann3; Anter El-Azab4; Jian Gan1; David Hurley1; 1Idaho National Laboratory; 2Ohio State University; 3Air Force Research Laboratory; 4Purdue University
A fundamental understanding of radiation effects on thermal transport is critical for the development of advanced nuclear fuels. In this talk, ion irradiation is used to seed atomic-to-nanoscale defects of controllable size and density in single crystal thorium dioxide (ThO2). The influence of these microstructural defects on the thermal properties of ThO2 is explored. Lattice defects are characterized using optical spectroscopy and transmission electron microscopy. Mesoscale measurements of thermal transport properties within the damaged region are performed using a laser-based modulated thermoreflectance technique. Measurements as a function of dose and temperature are analyzed using the classical Klemens-Callaway approach, to determine the impact of point and extended defect types on the thermal properties of ThO2. These results will provide further insight into the role of irradiation-induced defects in limiting phonon-mediated thermal transport in ceramics, and enable validation of model predictions based on the Boltzmann transport formalism
10:10 AM Invited
Phase-dictated Thermal Conductivity Response in Carbon Systems Exposed to Ion Irradiation: Ethan Scott1; Khalid Hattar2; Jeffrey Braun1; Sean King3; Mark Goorsky4; Patrick Hopkins1; 1University of Virginia; 2Sandia National Laboratories; 3Intel Corporation ; 4University of California Los Angeles
Doping through ion implantation has long been used to tailor the band structure and electronic properties of materials used in device applications. However, this process introduces defects into the material lattice which act as scattering sites for phonons, thereby reducing the thermal conductivity. Furthermore, nuances of the implantation process and characteristics of the ion species and target have a significant impact upon the thermal response of the implanted material. We demonstrate this in two CVD-based variants of carbon, polycrystalline diamond and diamond-like amorphous carbon. While heavy implantation of a crystalline target yields amorphization and a corresponding reduction in thermal conductivity, in the other extreme, implantation of the amorphous phase can produce a densification, thereby increasing the thermal conductivity. In this presentation, we highlight the application of thermoreflectance-based characterization techniques for deeper insight into the thermal response, and contrast the disparate responses of this material between crystalline phases.
10:35 AM Invited
Thermal Transport Behavior of U-50Zr at the Mesoscale: Before and After Irradiation: Zilong Hua1; Tiankai Yao1; Amey Khanolkar1; Cody Dennett1; Xiaxin Ding1; Krzysztof Gofryk1; Michael Benson1; Lingfeng He1; Jian Gan1; David Hurley1; 1Idaho National Laboratory
The U-Zr based metallic fuel is a promising candidate for the next generation of fast reactors. Accurate knowledge of thermal conductivity degradation under irradiation is key to understanding microstructural evolution and fuel performance. It is thus necessary to investigate thermal transport on the scale of damage accumulation. In this talk, recent research results of intragranular thermal conductivity in three U-50Zr phases, γ-, ω-, and δ-, and the influence of ion-irradiation, are reported. Our results reveal that different microstructures associated with the three phases are explicitly reflected in the thermal transport behavior of the pristine samples. Specifically, the hexagonal δ-phase shows significant thermal anisotropy. After irradiation, the thermal transport behavior of the three U-50Zr samples changes significantly. Transmission electron microscopy is used to understand the impact of irradiation microstructure on thermal conductivity. These new insights are expected to aid in fuel performance modeling and fuel design.
11:00 AM Invited
Non-magnetic Kondo Effect in Eelta-UZr2: Xiaxin Ding1; Kaya Wei2; Tiankai Yao1; Ryan Baumbach2; Krzysztof Gofryk1; 1Idaho National Laboratory; 2National High Magnetic Field Laboratory
Previously, we found an upturn of the electrical resistivity of UZr2 with a minimum at around 15 K and positive magnetoresistance [1]. To understand the nature of this unusual behavior and the source of the additional scattering mechanism of the conduction electrons at low temperatures, we have performed detailed low-temperature transport studies (down to 0.1 K) of this material under applied magnetic fields (up to 9 T). We find that the temperature dependence of magnetoresistance is independent of magnetic fields as high as 9 T. This is in agreement with the orbital Kondo resonance effect that should be weakly influenced by the magnetic field. It is also established that a two-level system determines the low-temperature thermal properties of materials with the disorder and a similar anomalous term is observed in the low temperature dependence of heat capacity of this material.[1] X. Ding et al., Phil. Mag. Lett. (under review)