Multilayer Diffraction Reveals That Colloidal Superlattices Approach the Structural Perfection of Single Crystals

Area of Science:

• Materials Science
• Nanotechnology
• Crystallography

Background:

• Colloidal superlattices, composed of ordered nanocrystals, present challenges in quantifying structural order.
• Achieving precise structural characterization is crucial for understanding and utilizing these advanced materials.

Purpose of the Study:

• To develop and validate a novel method for accurately determining the structural perfection of colloidal superlattices.
• To quantify nanocrystal size, interparticle spacing, and their fluctuations in self-assembled nanomaterials.

Main Methods:

• A multilayer diffraction method was employed, treating nanocrystals as self-probing interferometer components.
• X-ray diffraction patterns were analyzed using a laboratory-grade diffractometer and an open-source fitting algorithm.
• The method accurately determined nanocrystal size, interparticle spacing, and fluctuations.

Main Results:

• The study successfully quantified structural order in CsPbBr3 and PbS colloidal superlattices.
• Average nanocrystal displacements ranged from 0.33 to 1.43 Å, serving as a figure of merit for structural perfection.
• The determined displacements approach values found in traditional atomic crystals, indicating high structural integrity.

Conclusions:

• The developed multilayer diffraction method offers a reliable approach to assess the structural perfection of colloidal superlattices.
• This technique enables precise characterization of nanocrystal assembly, crucial for materials science applications.
• The findings demonstrate that certain colloidal superlattices exhibit a degree of structural order comparable to conventional crystalline materials.