ACrF₃ Jahn-Teller-Distorted Fluoroperovskites: Expanding to RbCrF₃ and CsCrF₃.

Area of Science:

• Solid State Chemistry
• Materials Science
• Crystallography

Background:

• The Jahn-Teller effect significantly distorts CrF6 octahedra in Cr(II) fluoroperovskites.
• A comprehensive understanding of A-site cation influences on A-site fluoroperovskites is lacking.

Purpose of the Study:

• To synthesize and characterize RbCrF3 and CsCrF3, completing the investigation of A-site cation effects in A-CrF3 fluoroperovskites.
• To elucidate the structural and magnetic properties of these compounds, focusing on the role of the Jahn-Teller effect.

Main Methods:

• Wet-chemical synthesis for stabilizing Cr(II).
• Powder X-ray diffraction for crystal structure determination.
• Magnetic susceptibility measurements to determine magnetic properties.

Main Results:

• RbCrF3 predominantly adopts the P4/mbm space group with stacking faults (5-10% I4/mcm).
• CsCrF3 exhibits a two-phase coexistence of I4/mcm and P4/mbm polymorphs.
• Both compounds show antiferromagnetic interactions with Weiss temperatures of -12 K and Néel temperatures of 50 K (RbCrF3) and 47 K (CsCrF3).

Conclusions:

• The study highlights the interplay between A-site cations and the Jahn-Teller effect on CrF6 octahedra.
• Structural distortions and magnetic behaviors are consistent with S=2 spin configurations.
• The findings contribute to a complete understanding of the A-CrF3 series.