Visualization of Solid-State Synthesis for Chalcogenide Na Superionic Conductors by in-situ Neutron Diffraction.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Chalcogenide superionic sodium conductors are promising solid electrolytes for all-solid-state sodium batteries.
• High energy density, safety, and cost-effectiveness are key advantages of these materials.
• Synthesis methods significantly impact crystal structure and ionic conductivity.

Purpose of the Study:

• To understand the structural evolution during the solid-state synthesis of chalcogenide sodium-ion conductors.
• To investigate the real-time structural changes using in-situ neutron diffraction.
• To evaluate the effect of selenium doping on synthesis and structural properties.

Main Methods:

• In-situ time-of-flight neutron diffraction (ND) for tracking structural changes.
• Solid-state synthesis of Na3SbS4 and Na3SbS3.5Se0.5.
• Theoretical simulations to complement experimental observations.

Main Results:

• A fast, one-step solid-state reaction was observed for both Na3SbS4 and Na3SbS3.5Se0.5.
• A molten process occurred upon heating, followed by recrystallization and a cubic-to-tetragonal phase transition upon cooling.
• Selenium doping influenced reaction temperatures, lattice parameters, and structural stability.

Conclusions:

• In-situ neutron diffraction provides critical insights into the synthesis of chalcogenide sodium-ion conductors.
• Understanding these structural dynamics is essential for optimizing synthesis and designing new solid electrolytes.
• The findings aid in the development of advanced solid-state sodium batteries.