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Understanding Negative Thermal Expansion materials (NTE) is critical to develop materials with tunable volumetric changes as a function of temperature. ScF₃ has attracted attention because of its simple chemical structure and the extended range where NTE is observed (up to 1100K). Measuring elastic moduli can bring light on the interatomic potentials being proposed to explain the NTE.
We use Resonant Ultrasound Spectroscopy measurements to determine the resonant spectra as function of temperature from 4 to 400K using a large single crystal of ScF₃. We also measure sound attenuation extracted from the peak’s width of representative resonances where we find evidence of a dissipative process below 30K, which coincides with an upturn observed in the elastic moduli.