Formation of Rare-Earth Hydroxycarbonate Shells on β-NaTRF₄ Nanoparticles under Mild Conditions

Multifunctional nanomaterials have emerged as promising platforms for applications in nanomedicine, theranostics, catalysis, and sensing. However, integrating multiple functionalities into a single system often imposes synthetic and structural design challenges. We previously showed that rare earth (RE) hydroxycarbonates act as kinetically stable precursors for different phases. In this work, we studied the formation of a RE hydroxycarbonate shell over NaGdF₄ nanoparticles enabling later conversion into oxide shells to generate mixed core@shell structures. Our results demonstrate the feasibility of hydroxycarbonate shell growth over β-NaGdF₄ nanoparticles and provide a route towards new multifunctional mixed-phase core@shell nanostructures.