Pack Cementation Route to Ag₂Se: Correlating Structure, Phase Formation, and Thermoelectric Performance

Area of Science:

• Materials Science
• Solid State Chemistry
• Thermoelectrics

Background:

• Silver selenide (Ag2Se) is a key thermoelectric material for near-room-temperature applications.
• Scalable fabrication of Ag2Se is hindered by conventional synthesis limitations and sensitivity to processing conditions.

Purpose of the Study:

• Introduce pack cementation as a novel, cost-effective, and industrially viable method for Ag2Se powder production.
• Investigate the impact of synthesis parameters on Ag2Se phase, composition, and microstructure.
• Establish structure-property relationships for optimized thermoelectric performance.

Main Methods:

• Utilized the pack cementation technique for synthesizing beta-silver selenide (β-Ag2Se) powders.
• Analyzed phase formation, composition, and microstructure using various characterization methods.
• Evaluated thermoelectric properties, including the figure of merit (ZT), as a function of temperature.

Main Results:

• Successfully synthesized phase-pure orthorhombic β-Ag2Se with near-stoichiometric composition and uniform microstructure.
• Phase purity was maintained after consolidation, with no secondary phases observed.
• Achieved a maximum thermoelectric figure of merit (ZT) of 0.63 at 352 K, with stable performance up to 375 K.

Conclusions:

• Pack cementation is a viable route for producing high-quality Ag2Se with competitive thermoelectric efficiency.
• The developed method demonstrates potential for large-scale production and future optimization of Ag2Se.
• Clear structure-property correlations were established, guiding material design for enhanced thermoelectric applications.