Rational Pathways to Ordered Multianion Chalcogenides Using Retrosynthetic Crystal Chemistry

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Mixed-anion chalcogenides offer tunable properties for diverse applications.
• Anion ordering occurs in systems with multiple unique anion sites, unlike simple binary solid solutions.
• Predicting secondary chalcogen occupation in anion sites is crucial for material design.

Purpose of the Study:

• To predict Wyckoff positions for secondary chalcogens in single-anion hosts using crystallographic analysis and hard-soft acid-base principles.
• To guide the predictable synthesis of ordered sulfoselenide, selenotelluride, and sulfotelluride materials.
• To investigate ordering trends in ternary and quaternary chalcogenide systems, including 3D CsCu5Q3 and 2D NaCuZrQ3 structures.

Main Methods:

• Crystallographic analysis and hard-soft acid-base (HSAB) principles for predicting anion site occupation.
• High-temperature solid-state synthesis methods for preparing mixed-chalcogenide samples.
• Single-crystal X-ray diffraction for structural characterization.
• Density-functional theory (DFT) calculations to corroborate experimental findings.

Main Results:

• Ordering in mixed-anion chalcogenides is driven by the size and bonding variance of chalcogen anions.
• The degree of ordering depends on the local chemistry of anion sites and the specific chalcogen combination.
• Mixed-chalcogen products can form distinct phases not observed in single-anion end members, such as KCuZrTe2S.
• A reverse-engineering approach, inspired by retrosynthetic analysis, aids in understanding and discovering heteroanionic phenomena.

Conclusions:

• The study provides a predictive framework for synthesizing ordered mixed-anion chalcogenides.
• Understanding anion ordering is key to controlling material properties and discovering new phases.
• The developed approach accelerates the discovery and comprehension of complex heteroanionic materials.