Electron-poor antimonides: complex framework structures with narrow band gaps and low thermal conductivity

Area of Science:

• Materials Science
• Solid State Physics
• Inorganic Chemistry

Background:

• Binary zinc/cadmium antimonides and ternary indium relatives exhibit complex crystal structures.
• These materials possess narrow band gaps near the Fermi level, classifying them as electron-poor framework semiconductors (EPFS).
• EPFS materials, composed of metal and semimetal atoms, feature weakly polar frameworks with multi-center bonded entities.

Purpose of the Study:

• To investigate the structural and electronic properties of electron-poor antimonides.
• To explore the potential of these materials for thermoelectric applications.
• To understand the relationship between bonding characteristics and material complexity.

Main Methods:

• Crystallographic analysis to determine complex structures.
• Electronic structure calculations to identify narrow band gaps.
• Thermal property measurements to assess thermoelectric potential and stability.

Main Results:

• Electron-poor antimonides demonstrate promising thermoelectric properties.
• Remarkably low thermal conductivity was observed in these materials.
• Limited thermal stability, due to polymorphism and low decomposition temperatures (below 600 K), was identified.

Conclusions:

• The localized multi-center bonding is key to the structural complexity of these semiconductors.
• Electron-poor antimonides are related to boron allotropes in their electronic characteristics.
• Despite thermal stability limitations, these materials show significant potential for thermoelectric devices.