Predicting Distortion Magnitudes in Prussian Blue Analogues

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Prussian blue analogues (PBAs) are a class of hybrid perovskite materials with diverse applications.
• Understanding the factors governing structural distortions in PBAs is crucial for tuning their properties.

Purpose of the Study:

• To establish a direct link between the composition of PBAs and their tendency to exhibit structural distortions.
• To identify a predictive model for the presence and extent of distortions in PBAs.

Main Methods:

• Derivation of an expression based on electrostatic and harmonic potential considerations.
• Analysis of a wide range of Prussian blue analogues.
• Introduction of a geometric tolerance factor to quantify distortions.

Main Results:

• A straightforward expression was derived, connecting PBA composition to structural distortion propensity.
• A critical threshold value was identified, distinguishing between undistorted and distorted PBAs.
• The degree of distortion above the threshold is governed by the geometric tolerance factor.

Conclusions:

• The derived model successfully rationalizes the observed structural behavior of numerous PBAs.
• This work differentiates the structural chemistry of PBAs from other hybrid perovskites.
• The findings provide a predictive framework for designing PBAs with desired structural characteristics.