Long-Distance Lanthanide Migration Regulated by Interfacial Lattice Strain in Nanostructure

Interfacial strain engineering, achieved through the precise control of lattice mismatch, holds implications for both fundamental and technological applications. However, unravelling the correlation between interfacial lattice strain and material properties at the nanoscale remains challenging due to limitation in regulating both the type and magnitude of strain at the nanoscale. Here, we observe long-distance ion migration induced by interfacial lattice strain in a series of lanthanide core-shell nanofluorides. By deliberately manipulating interfacial strain using lanthanide cations with varying ionic radii, the lattice mismatch promotes lanthanide migration across heterostructure interfaces and thus influences crystal growth dynamics and subsequent optical features. Notably, when lattice mismatch exceeds 5.1%, lanthanide ions within core nanoparticles can diffuse up to 13 nm along the [1000] crystallographic direction, crossing the interface and migrating into the shell layer of hexagonal-phase NaLnF ₄ core-shell-shell nanolattices. Mechanistic investigation indicates that large interfacial tensile strain and slow shell growth are beneficial for strain relaxation via ion diffusion. These findings provide new insights into strain-driven ion diffusion at the nanoscale and open avenues for novel heterogeneous nanocrystals development with precisely tailored structures and confined active ions. These advancements could promote a range of applications, including bioimaging, nanocatalysis, quantum information, and many others.