Polymorphic Control of CsGaE₂ (E = S, Se) Using Diorganyl Dichalcogenide Precursors.

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystallography

Background:

• Diorganyl dichalcogenides (R-E-E-R) offer tunable C-E bond reactivity for polymorphic control.
• Their application is extended to non-close-packed alkali-metal-based chalcogenides.

Purpose of the Study:

• To demonstrate the selective synthesis of CsGaE2 (E = S, Se) polymorphs using diorganyl dichalcogenides.
• To investigate the influence of C-E bond strength and temperature on phase formation.

Main Methods:

• Utilized diorganyl dichalcogenides for synthesis of CsGaE2 (E = S, Se) polymorphs.
• Employed varying temperatures and controlled C-E bond reactivity.
• Conducted heat-treatment studies to analyze phase stability and transitions.

Main Results:

• Achieved selective synthesis of CsGaE2 (E = S, Se) polymorphs.
• Identified that weaker C-E bonds or higher temperatures favor stable mC64 phases.
• Stronger C-E bonds or lower temperatures yield metastable mC16 phases.
• Observed pronounced metastability in CsGaSe2-mC16 and irreversible transition in CsGaS2.

Conclusions:

• Diorganyl dichalcogenides are effective for controlling polymorphism in alkali-metal-based chalcogenides.
• Phase selection is governed by C-E bond strength and reaction temperature.
• The study highlights the metastability of specific CsGaE2 polymorphs and their transition behaviors.