Thermal conductivity reduction in (Zr_0.25Ta_0.25Nb_0.25Ti_0.25)C high entropy carbide from extrinsic lattice defects

ABSTRACT

High entropy carbides ceramics with randomly-distributed multiple principal cations have shown high temperature stability, low thermal conductivity, and possible radiation tolerance. While chemical disorder has been shown to suppress thermal conductivity in these materials, little investigation has been made on the effects of additional, extrinsically-generated structural defects on thermal transport. Here, (Zr${}_{0.25}$Ta${}_{0.25}$Nb${}_{0.25}$Ti${}_{0.25}$)C is exposed to Zr ions to generate a micron-scale, structural-defect-bearing layer. The reduction in lattice thermal transport is measured using laser thermoreflectance. Conductivity changes from different implantation temperatures suggest dislocation loops contribute little to phonon scattering while nanoscale defects serve as effective scatterers, offering a pathway for thermal engineering.

GRAPHICAL ABSTRACT

KEYWORDS:

• High entropy ceramic
• defects
• thermal transport

Acknowledgments

The authors would like to thank S.G. Rosenberg and M. Meyerman at SNL for performing XPS measurements. The views expressed in this article do not necessarily represent the views of the U.S. DOE of the United States Government.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported through the INL Laboratory Directed Research & Development Program under U.S. Department of Energy Idaho Operations Office Contract DE-AC07-05ID14517. C.A.D. and Z.H. acknowledge support from the Center for Thermal Energy Transport under Irradiation (TETI), an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the DOE Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE's National Nuclear Security Administration under contact DE-NA-0003525.