Is RuAs₂ a candidate for high temperature thermoelectric applications?

Area of Science:

• Materials Science
• Solid State Physics
• Inorganic Chemistry

Background:

• Ruthenium arsenide (RuAs2) is a mineral-inspired material with potential thermoelectric applications.
• Its high stability and attractive electronic band structure warrant investigation for energy conversion.

Purpose of the Study:

• To synthesize and characterize phase-pure polycrystalline ruthenium arsenide (RuAs2).
• To evaluate the thermoelectric properties and structural stability of RuAs2.
• To identify strategies for improving the thermoelectric performance of RuAs2.

Main Methods:

• Spark Plasma Sintering (SPS) for densification of RuAs2.
• Temperature-dependent electrical resistivity measurements to determine band gap.
• Density Functional Theory (DFT) calculations for band structure analysis.
• Synchrotron powder X-ray diffraction and Rietveld refinement for structural stability assessment.

Main Results:

• Synthesized phase-pure, n-type RuAs2 with an indirect band gap of 0.69 eV (experimental) and 0.64 eV (DFT).
• Observed high room temperature thermal conductivity (16 W m⁻¹ K⁻¹) and electrical resistivity (170 mΩ cm), resulting in modest intrinsic thermoelectric properties.
• Confirmed RuAs2 as a stable line phase up to 1000 K under various conditions (air, vacuum, powder, pellet).

Conclusions:

• Ruthenium arsenide (RuAs2) exhibits excellent structural stability, making it a robust material candidate.
• The intrinsic thermoelectric properties of RuAs2 are moderate, suggesting a need for material optimization.
• Chemical modification, particularly at the arsenic (As) site, is recommended to enhance the thermoelectric performance of RuAs2.