Fabrication of single-crystal long wires of Ru60Mo15W25 alloy and anisotropy of electrical and thermal properties

Ru-Mo-W alloy (Ruscaloy) single-crystal wires demonstrate high-efficiency vacuum deposition for fabricating organic light-emitting diodes, providing a promising alternative to conventional polycrystalline Ta heaters. In this study, long Ru 60 Mo 15 W 25 wires were fabricated using the dewetting micro-pulling-down (μ-PD) method to investigate their electrical and thermal properties. Due to the capillary-based solidification mechanism, the wires retained a uniform composition along their length (>30 m). Electrical resistivity measurements, the calculated thermal expansion coefficient, and indentation tests revealed anisotropic properties of the wires: the c-axis generally exhibited larger electrical resistivity and thermal expansion than the basal plane directions. First-principles calculations were performed to evaluate the effects of Mo and W concentration and temperature on electrical resistivity and electronic thermal conductivity. The calculated resistivity values agreed with experimental data with deviations within approximately 15 %, indicating that the computational approach effectively complements experiments. Overall, these findings provide a solid foundation for optimizing the design and application of Ru 60 Mo 15 W 25 single-crystal wires as high-temperature resistive heaters. • Continuous dewetting μ-PD method enabled meter-scale single-crystal Ru60Mo15W25 wires. • Minimal compositional variation and tunable crystal orientation achieved by adjusting pulling rate. • Anisotropic electrical resistivity, thermal expansion, and mechanical properties elucidated. • First-principles calculations reveal composition- and temperature-dependent transport properties. • Potential applications in resistive heaters for OLED fabrication and wire-based additive manufacturing.