Unraveling Epitaxial Habits in the NaLnF4 System for Color Multiplexing at the Single‐Particle Level

Abstract

AbstractWe report an epitaxial growth technique for scalable production of hybrid sodium rare‐earth fluoride (NaLnF4) microcrystals, including NaYF4, NaYbF4, and NaLuF4 material systems. The single crystalline nature of the as‐synthesized products makes them strong upconversion emission. The freedom of combining a lanthanide activator (Er3+ or Tm3+) with a sensitizer (Yb3+) at various doping concentrations readily gives access to color multiplexing at the single‐particle level. Our kinetic and thermodynamic investigations on the epitaxial growth of core–shell microcrystals using NaLnF4 particle seeds suggest that within a certain size regime it is plausible to exert precise control over shell thickness and growth orientation under hydrothermal conditions.