Controlled Synthesis of a New Class of Heterostructured Metal Oxides (Cerium, Thorium, Uranium)/Calcium Fluoride Core‐Shell Nanocrystals With Atomically Coherent Interfaces

ABSTRACT Heterostructured nanocrystals (NCs) integrating chemically and/or structurally distinct materials are of significant interest due to their potential to exhibit multiple functionalities or unconventional properties. However, the development of such materials remains limited, primarily due to crystallographic incompatibilities and synthesis challenges. Here, we report the synthesis and structural characterization of a new class of metal oxide‐based (Ce, Th, or U) heterostructures with calcium fluoride featuring core‐shell architectures with precise control over both morphology and shell thickness. Powder x‐ray diffraction (PXRD) and high‐resolution scanning/transmission electron microscopy techniques confirm the formation of high‐quality single‐crystalline particles coupling metal oxide (Ce, Th, or U) and calcium fluoride domains through a structurally coherent but chemically complex intermixed oxide‐fluoride interface—an unprecedented observation in cerium and actinide nanochemistry. These novel materials have been designed to anticipate their future doping with therapeutic alpha particle‐emitting radionuclides (α‐emitters) such as 227 Th or 230 U for locoregional targeted alpha therapy (TAT). It is anticipated that the reported heterostructured core‐shell NCs will offer a promising platform for preclinical investigations to determine the full potential and interest of inorganic core‐shell NCs, especially CeO 2 / CaF 2 , for TAT application.