Lanthanide-doped KYb3F10 crystals: controllable phases, rich morphologies and Tb3+/Eu3+ down-conversion emission

Abstract

KYb₃F₁₀:Ln³⁺ (Ln = Er, Ho, Tb, Gd, Eu, Sm, Ce and La) micro/nanocrystals with abundant morphologies were synthesized via a one-step hydrothermal route without employing any surfactants. Furthermore, the homogeneous and well-defined KYb₃F₁₀ crystals with truncated tetragonal bipyramidal, nanoparticle, nanospherical, microtubular and rugby ball shapes were achieved by manipulating the different environments of crystal growth, such as increasing the concentration of F⁻, adjusting the pH, using different fluorine sources and adding trisodium citrate. XRD, SEM, EDS and PL as well as lifetime analysis were used to characterize the products. The obtained KYb₃F₁₀:Ln³⁺ products showed bright emission colors red (Eu³⁺) and green (Tb³⁺), respectively. It has been found that larger crystal shapes/sizes can greatly enhance their luminescence properties and lifetimes due to their high crystallinity and few defects on the crystal surface. The as-synthesized KYb₃F₁₀:Eu³⁺/Tb³⁺ products might be potentially applied in multicolor lighting and displays.