Orientation-dependent transport properties of Cu3Sn

• Published in: Acta materialia 2022-04, Vol.227, p.117671, Article 117671
• Main Authors: Daeumer, Matthias, Sandoval, Ernesto D., Azizi, Arad, Bagheri, Morteza H., Bae, In-Tae, Panta, Sitaram, Koulakova, Ekaterina A., Cotts, Eric, Arvin, Charles L., Kolmogorov, Aleksey N., Schiffres, Scott N.
• Format: Article
• Language: English
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2022.117671

Cu3Sn, a well-known intermetallic compound with a high melting temperature and thermal stability, has found numerous applications in microelectronics, 3D printing, and catalysis. However, the relationship between the material's thermal conductivity anisotropy and its complex anti-phase boundary superstructure is not well understood. Here, frequency domain thermoreflectance was used to map the thermal conductivity variation across the surface of arc-melted polycrystalline Cu3Sn. Complementary electron backscatter diffraction and transmission electron microscopy revealed the thermal conductivity in the principal a, b, and c orientations to be 57.6, 58.9, and 67.2 W/m-K, respectively. Density functional theory calculations for several Cu3Sn superstructures helped examine thermodynamic stability factors and evaluate the direction-resolved electron transport properties in the relaxation time approximation. The analysis of computed temperature- and composition-dependent free energies suggests metastability of the known long-period Cu3Sn superstructures while the transport calculations indicate a small directional variation in the thermal conductivity. The ∼15% anisotropy measured and computed in this study is well below previously reported experimental values for samples grown by liquid-phase electroepitaxy. [Display omitted]