DOE OSTI · 3429757
Electrostatic Superlattices Beyond 1:1 Stoichiometry
Abstract
ABSTRACT Exotic nanoparticle superstructures can be accessed by harnessing nanoparticle softness and charge regulation, features often viewed as obstacles to structural control. Here, we show that regulated charge mismatch in polymer‐grafted nanoparticles enables the assembly of high‐stoichiometry cubic superlattices. By co‐tuning grafting density, particle size, and bulk composition, we realize ionic‐lattice analogues, such as and , as well as single‐component and superlattices without atomic counterparts. The superlattice has recently been identified theoretically as a photonic band‐gap lattice. These phases emerge from a 1:1 “parent” lattice when local charge neutrality cannot be satisfied, driving either progressive interstitial filling or reorganization into a larger basis. For instance, the systematic occupation of ZnS tetrahedral sites yields , while ligand‐swapping symmetry breaking converts CsCl into . Upon heating, the assemblies exhibit reversible lattice contraction and pronounced negative thermal expansion. Furthermore, the energetic penalty for defects increases with nanoparticle size, facilitating the scalable production of high‐quality, open superlattices for photonic applications.
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Nayak, Binay P. [Department of Chemical and Biological Engineering Iowa State University Ames USA; Division of Materials Sciences and Engineering Ames National Laboratory Ames USA] (ORCID:0000000239954114), Kakkar, Prapti [Department of Chemical and Biological Engineering Iowa State University Ames USA; Division of Materials Sciences and Engineering Ames National Laboratory Ames USA] (ORCID:0000000273834642), Korba, Wesley P. [Division of Materials Sciences and Engineering Ames National Laboratory Ames USA; Department of Physics and Astronomy Iowa State University Ames USA], Zhang, Honghu [National Synchrotron Light Source II Brookhaven National Laboratory Upton USA] (ORCID:0000000317847825), Wang, Wenjie [Division of Materials Sciences and Engineering Ames National Laboratory Ames USA], Mallapragada, Surya K. [Department of Chemical and Biological Engineering Iowa State University Ames USA; Division of Materials Sciences and Engineering Ames National Laboratory Ames USA], Travesset, Alex [Division of Materials Sciences and Engineering Ames National Laboratory Ames USA; Department of Physics and Astronomy Iowa State University Ames USA] (ORCID:0000000170309570), Vaknin, David [Division of Materials Sciences and Engineering Ames National Laboratory Ames USA; Department of Physics and Astronomy Iowa State University Ames USA] (ORCID:0000000208999248). 2026-08-10. Electrostatic Superlattices Beyond 1:1 Stoichiometry. https://doi.org/10.1002/adfm.77545
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