Extremely high electron mobility in a phonon-glass semimetal

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Electron mobility is crucial for charge-carrier transport, impacting thermoelectric and solar energy applications.
• Chemical disorder typically reduces electron mobility, posing a challenge for thermoelectric materials design.
• Reducing thermal conductivity via disorder is key for thermoelectrics, but often sacrifices mobility.

Purpose of the Study:

• To investigate the novel semimetal β-CuAgSe for its charge-transport properties.
• To explore the potential of β-CuAgSe to overcome the mobility degradation associated with chemical disorder in thermoelectric materials.
• To evaluate the impact of Ni doping on the electron mobility and thermoelectric performance of β-CuAgSe.

Main Methods:

• Synthesis of polycrystalline β-CuAgSe ingot.
• Characterization using magnetoresistance and Shubnikov de Haas oscillations measurements.
• Introduction of chemical and lattice disorder via Ni doping.
• Evaluation of thermoelectric figure of merit.

Main Results:

• β-CuAgSe exhibits a high-mobility small electron pocket derived from the Ag s-electron band.
• Ni doping significantly enhances electron mobility to 90,000 cm(2) V(-1) s(-1) at 10 K.
• Doping leads to increased magnetoresistance and an improved thermoelectric figure of merit.
• The material demonstrates a glassy lattice structure.

Conclusions:

• β-CuAgSe successfully overcomes the trade-off between disorder and mobility in thermoelectric materials.
• Ni-doped β-CuAgSe presents a promising new class of Ag-based layered semimetal thermoelectrics.
• The material's unique properties make it suitable for chemical engineering and advanced thermoelectric applications.