Vacancy-induced dislocations within grains for high-performance PbSe thermoelectrics

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Minimizing lattice thermal conductivity is crucial for efficient thermoelectric materials.
• Current strategies involve scattering phonons using interfaces and point defects.
• Scattering mid-frequency phonons via dislocations at grain boundaries also improves thermoelectric performance.

Purpose of the Study:

• To propose and investigate a vacancy engineering strategy for creating dense dislocations within grains.
• To reduce lattice thermal conductivity and enhance the thermoelectric figure of merit (zT) in solid solutions.

Main Methods:

• Introduced cation vacancies in Pb1-xSb2x/3Se solid solutions.
• Utilized thermal annealing to annihilate vacancies, forming dislocations homogeneously within grains.
• Measured lattice thermal conductivity and thermoelectric figure of merit.

Main Results:

• Achieved a significantly low lattice thermal conductivity of 0.4 W m⁻¹ K⁻¹.
• Demonstrated a high thermoelectric figure of merit.
• Explained results using a dislocation scattering model.

Conclusions:

• Vacancy engineering is an effective strategy for creating dislocations and reducing thermal conductivity in thermoelectrics.
• This method homogeneously distributes dislocations within grains, enhancing thermoelectric performance.
• The proposed strategy is applicable to various solid solution thermoelectrics for improved zT.