Boosting Thermoelectric Properties of AgBi₃(SeS_1-)₅ Solid Solution via Entropy Engineering

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• AgBi3S5 is an eco-friendly n-type thermoelectric material with low thermal conductivity due to its complex monoclinic structure.
• Poor electrical properties currently limit the thermoelectric performance of AgBi3S5.
• Configurational entropy engineering is a promising strategy to improve thermoelectric materials.

Purpose of the Study:

• To enhance the thermoelectric properties of AgBi3S5 through a combination of carrier modulation and entropy engineering.
• To investigate the effect of selenium (Se) substitution and anion deficiency on the thermoelectric performance of AgBi3S5.
• To synthesize and characterize a series of AgBi3(Se_xS_{1-x})5.08 bulk materials.

Main Methods:

• Synthesis of AgBi3(Se_xS_{1-x})5.08 bulks using melting-annealing and spark plasma sintering.
• Systematic substitution of sulfur (S) with selenium (Se) to increase configurational entropy.
• Anion deficiency modulation to optimize carrier concentration and electrical transport properties.

Main Results:

• Se substitution significantly increased configurational entropy, leading to a dramatic decrease in thermal conductivity.
• Anion deficiency modulation effectively optimized carrier concentration and electrical transport properties.
• The AgBi3(Se0.9S0.1)5.08 sample achieved a peak thermoelectric figure of merit (ZT) of 0.42 at 723 K, nearly double that of pristine AgBi3S5.

Conclusions:

• Combining carrier modulation and entropy engineering is an effective strategy for enhancing thermoelectric materials.
• Entropy engineering, particularly through Se substitution, offers a new pathway for improving the thermoelectric performance of AgBi3S5.
• The developed AgBi3(Se_xS_{1-x})5.08 materials show potential for practical thermoelectric applications.