超出1:1化学计量比的静电超晶格
Electrostatic Superlattices beyond 1:1 Stoichiometry
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中文总结 AI 辅助
该研究利用聚合物接枝纳米颗粒的电荷失配，组装出含A₃等新型超晶格，其可实现可逆负热膨胀，且大颗粒利于制备高质量开放超晶格，适用于光子应用。
中文摘要 AI 辅助
利用纳米颗粒的柔软性和电荷调控特性可制备出奇特的纳米颗粒超结构，而这些特性常被视为结构控制的障碍。本文中，我们证明聚合物接枝纳米颗粒的调控电荷失配可实现高化学计量比立方超晶格的组装。通过协同调控接枝密度、颗粒尺寸和本体组成，我们成功制备出类似CaF₂和Th₃P₄的离子晶格类似物，以及无原子对应物的单组分A₃和A₇超晶格。A₃晶格近期被理论确认为光子带隙晶格。当局部电中性无法满足时，这些相从1:1“母相”晶格中产生，驱动逐步间隙填充或重组为更大基元。例如，ZnS四面体位点的系统占据产生CaF₂，而配体交换对称性破缺将CsCl转化为Th₃P₄。加热时，这些组装体表现出可逆晶格收缩和显著的负热膨胀。此外，缺陷的能量惩罚随纳米颗粒尺寸增大而增加，有助于规模化生产高质量、开放型超晶格，适用于光子应用。
英文摘要
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 CaF2 and Th3P4, as well as single-component A3 and A7 superlattices without atomic counterparts. The A3 lattice 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 CaF2, while ligand-swapping symmetry breaking converts CsCl into Th3P4. 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.
