A New Cation-Ordered Structure Type with Multiple Thermal Redistributions in Co₂ InSbO₆

Area of Science:

• Solid-state chemistry and materials science.
• Exploration of crystal structures and cation ordering in ABO3 derivatives.

Background:

• Cation ordering in solids is crucial for tuning physical properties.
• Ilmenite (FeTiO3) and LiNbO3 are known corundum structure derivatives.
• A hypothetical R32 symmetry ABO3 derivative has remained undiscovered.

Purpose of the Study:

• To synthesize and characterize a new ABO3 derivative with R32 symmetry.
• To investigate cation redistribution pathways and their impact on material properties.
• To explore the potential for discovering novel metastable corundum derivatives.

Main Methods:

• High-pressure synthesis of Co2InSbO6.
• In-situ heating experiments to observe cation redistribution.
• Structural and magnetic property characterization.

Main Results:

• Discovery of a novel ordered-R32 A2BCO6 variant of the corundum structure in Co2InSbO6.
• Observed two cation redistribution events in Co2InSbO6 upon heating, forming LiNbO3-type variants.
• The final ordered-LiNbO3 product exhibits a sharp ferrimagnetic transition, distinct from the initial R32 phase.

Conclusions:

• Co2InSbO6 represents the first observed ABO3 derivative with R32 symmetry.
• Cation redistribution significantly influences the magnetic properties of these corundum derivatives.
• High-pressure synthesis is a promising route for discovering new metastable corundum derivatives and R32 structured materials.