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arXiv · 2602.23247

Accounting for the length-scale dependence of thermal diffusivity in 3C-SiC measured with transient thermal gratings

Keshav Vasudeva·Samuel Huberman·Angus P. C. Wylie·Maxwell Rae·Joey Demiane·Jamal A. Haibeh·Elena Botica-Artalejo·Kevin B. Woller·Michael P. Short·Sara E. Ferry
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Abstract

Pump-probe optical methods like transient grating spectroscopy (TGS) enable rapid, nondestructive thermoelastic property measurements. But, in phonon-dominated ceramics, they can underpredict bulk thermal diffusivity when long mean free path (MFP) phonons do not equilibrate over experimental length scales. We combine in situ TGS with Si4+ ion irradiation of CVD 3C-SiC (300 and 550C, 0.5-1 dpa) and density functional theory informed Boltzmann transport equation solutions to understand the origins of this offset. We show how the discrepancy between laser flash analysis (LFA) and TGS-measured thermal diffusivity varies with grain-boundary density, temperature, and defect concentration. We introduce a dimensionless suppression factor that accounts for this discrepancy and demonstrate its utility by using it to show an agreement between the thermal defect resistance of neutron irradiated 3C-SiC (measured using LFA) and ion irradiated 3C-SiC (measured using TGS). This theory-informed experimental framework enables quantitative, in situ tracking of ion irradiation damage induced thermal transport degradation in ceramics.

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Keshav Vasudeva, Samuel Huberman, Angus P. C. Wylie, Maxwell Rae, Joey Demiane, Jamal A. Haibeh, Elena Botica-Artalejo, Kevin B. Woller, Michael P. Short, Sara E. Ferry. 2026-02-26. Accounting for the length-scale dependence of thermal diffusivity in 3C-SiC measured with transient thermal gratings. https://arxiv.org/abs/2602.23247

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