Ella Kartika Pek
- Name
- Dr. Ella Kartika Pek
- Institution
- Idaho National Laboratory
- Position
- Postdoctoral Research Associate
- Affiliation
- MRS member, TMS member
- h-Index
- 4
- ORCID
- 0009-0000-2553-2511
- Biography
Dr. Ella K. Pek is currently Postdoctoral Research Associate at Idaho National Laboratory, with a Ph.D. in Materials Science & Engineering from the University of Illinois at Urbana-Champaign. She has extensive expertise in laser-based thermal transport studies, particularly using time-domain thermoreflectance (TDTR). Leveraging this expertise, she has the ability of characterizing and mapping the thermal properties of various materials:
- Thin films, superlattices (TDTR has the capability to be more sensitive to the thin film sample instead of the usual characterization that is more sensitive to the bulk properties)
- Actinide materials and irradiated materials, such as irradiated UO2, fission product’s effect on thermal conductivity of nuclear fuel (ThO2)
- low-dimensional quantum magnets, where TDTR can characterize another contribution to thermal conductivity (magnons, in addition to phonons)
Along with her expertise in laser-based thermal properties characterization, she leverages her expertise in Python to characterize interdiffusion coefficients. One of the applications of this skill was shown in her projects of analyzing interdiffusion coefficients of different coatings on Zircaloy-based accident tolerant fuel cladding. For this analysis, she utilized Python-based code (pydiffusion) to process composition data obtained through Electron Probe Microanalysis (EPMA).
Throughout her research projects, she developed expertise in programming with MATLAB and Python, and in various structural and chemical analytical tools, which helped her in characterizing her samples. These tools include Secondary Electron Microscope (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD), Rutherford Backscattering (RBS), Raman spectroscopy, and several physical vapor deposition (PVD) techniques.
Her other research interests, where she can leverage her skills, include:
- Nuclear Materials and Fuel Cladding
o characterizing irradiation defects and studying the effects of radiation on the thermal properties of nuclear fuels and fuel claddings
o analyzing diffusion coefficients and thermal behavior of materials used in nuclear reactors
- Advanced Measurement Techniques and Instrumentation
o Developing and optimizing advanced measurement systems for high-resolution thermal studies
o Enhancing thermal mapping and characterization techniques for applications in various materials
- High-Throughput Material Characterization
o Utilizing knowledge of thermal properties characterization to be applied to a high-throughput, in-situ online monitoring tool.
- Thin Films and Nanostructures
o Characterizing thermal, optical, and electrical properties of thin films and nanostructures
o Studying the impact of thickness, interfaces, and composition of material properties
- Expertise
- AFM, Cladding, Defects, Diffusion, Electrical Measurement (four point probe method), Interdiffusion, Nuclear Fuels, Raman, SEM, Structural, Thermal Transport, Thin Films
| "Experimental confirmation of first-principles thermal conductivity in Zirconium-doped ThO2" Zilong Hua, Amey Khanolkar, J. Matthew Mann, David B. Turner, Karl Rickert, Timothy A. Prusnick, Marat Khafizov, David H. Hurley, Linu Malakkal, Ella Kartika Pek, [2025] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2025.155756 · ISSN: 0022-3115 | |
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"Thermal conductivity mapping of oxidized SiC/SiC composites by time-domain thermoreflectance with heterodyne detection"
Zhe Cheng, Ella K. Pek, David G. Cahill, Xiaoyang Ji,
[2021]
Journal of the American Ceramic Society
· DOI: 10.1111/jace.17873
· EID: 2-s2.0-85105816554
· ISSN: 1551-2916
Silicon carbide/silicon carbide (SiC/SiC) composites are often used in oxidizing environments at high temperatures. Measurements of the thermal conductance of the oxide layer provide a way to better understand the oxidation process with high spatial resolution. We use time‐domain thermoreflectance (TDTR) to map the thermal conductance of the oxide layer and the thermal conductivity of the SiC/SiC composite with a spatial resolution of 3 μm. Heterodyne detection using a 50‐kHz‐modulated probe beam and a 10‐MHz‐modulated pump suppresses the coherent pick‐up and enables faster data acquisition than what has previously been possible using sequential demodulation. By analyzing the noise of the measured signals, we find that in the limit of small integration time constants or low laser powers, the dominant source of noise is the input noise of the preamplifier. The thermal conductance of the oxide that forms on the fiber region is lower than the oxide on the matrix due to small differences in thickness and thermal conductivity. |
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"Thermal conductivity of the n = 1-5 and 10 members of the (SrTiO3)n SrO Ruddlesden-Popper superlattices"
Ella K. Pek, Che-Hui Lee, Eugene J. Ragasa, Xue Xiong, Kiyoung Lee, Simon R. Phillpot, Aleksandr V. Chernatynskiy, David G. Cahill, Darrell G. Schlom, Natalie M. Dawley,
[2021]
Applied Physics Letters
· DOI: 10.1063/5.0037765
· EID: 2-s2.0-85102057667
· ISSN: 0003-6951
Unlike many superlattice structures, Ruddlesden–Popper phases have atomically abrupt interfaces useful for interrogating how periodic atomic layers affect thermal properties. Here, we measure the thermal conductivity in thin films of the n = 1–5 and 10 members of the (SrTiO3)nSrO Ruddlesden–Popper superlattices grown by molecular-beam epitaxy and compare the results to a single crystal of the n = 1 Ruddlesden–Popper SrLaAlO4. The thermal conductivity cross-plane to the superlattice layering (k33) is measured using time-domain thermoreflectance as a function of temperature and the results are compared to first-principles calculations. The thermal conductivity of this homologous series decreases with increasing interface density. Characterization by x-ray diffraction and scanning transmission electron microscopy confirms that these samples have a Ruddlesden–Popper superlattice structure. |
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| "High spatial resolution thermal conductivity mapping of SiC/SiC composites" John Brethauer, David G. Cahill, Ella Kartika Pek, [2020] Journal of Nuclear Materials · DOI: 10.1016/j.jnucmat.2020.152519 · EID: 2-s2.0-85091337100 · ISSN: 0022-3115 | |
| "Accurate thermoreflectance imaging of nano-features using thermal decay" Gregory Hohensee, Ella Pek, Wan Kuang, Kazuaki Yazawa, Ali Shakouri, Dustin Kendig, [2017] Proceedings of the 16th InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2017 · DOI: 10.1109/itherm.2017.7991852 · EID: 2-s2.0-85034454153 | |
| "Calibrated sub-micron temperature mapping of an operating plasmonic HAMR device by thermoreflectance imaging" Dustin Kendig, Ella Pek, Wan Kuang, Kazuaki Yazawa, Ali Shakouri, Gregory T. Hohensee, [2017] MRS Advances · DOI: 10.1557/adv.2017.438 · EID: 2-s2.0-85047204214 · ISSN: 2059-8521 | |
| "Nanoscale temperature of plasmonic HAMR heads by polymer imprint thermal mapping" Tan Nguyen, Ella Pek, Wan Kuang, Ozgun Suzer, Marc Finot, Gregory T. Hohensee, [2017] MRS Advances · DOI: 10.1557/adv.2017.439 · EID: 2-s2.0-85047185163 · ISSN: 2059-8521 | |
| "Pump-probe thermoreflectance measurements of critical interfaces for thermal management of HAMR heads" Mousumi M. Biswas, Ella Pek, Chris Lee, Min Zheng, Yingmin Wang, Chris Dames, Gregory T. Hohensee, [2017] MRS Advances · DOI: 10.1557/adv.2017.503 · EID: 2-s2.0-85047184939 · ISSN: 2059-8521 | |
| Source: ORCID/CrossRef using DOI | |
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The Nuclear Science User Facilities (NSUF) is the U.S. Department of Energy Office of Nuclear Energy's only designated nuclear energy user facility. Through peer-reviewed proposal processes, the NSUF provides researchers access to neutron, ion, and gamma irradiations, post-irradiation examination and beamline capabilities at Idaho National Laboratory and a diverse mix of university, national laboratory and industry partner institutions.
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