The mesoscale regulation of β-NaYF4:Yb3+/Er3+ with desired size and morphology via introducing Li+/K+ into a hydrothermal environment

Abstract

Herein we report the controllable synthesis of NaYF₄:Yb³⁺/Er³⁺via mesoscale regulation through the introduction of Li⁺/K⁺ into a hydrothermal system. The crystal evolution process of β-NaYF₄:Yb³⁺/Er³⁺ is investigated based on the reaction parameters. The mesoscale growth process includes four stages: (1) nucleation, (2) aggregation, (3) orientation growth, and (4) ripening. Through the introduction of Li⁺/K⁺ into the hydrothermal environment, super-small β-NaYF₄:Yb³⁺/Er³⁺ upconversion nanoparticles can be obtained.