KF-mediated controlled-synthesis of potassium ytterbium fluorides (doped with Er3+) with phase-dependent upconversion luminescence

Abstract

Potassium ytterbium fluorides with predictable crystal phases and architectures, such as KYb₃F₁₀ nanoplates, KYb₂F₇ nanoparticles, sub-microplates, sub-microrods, KYbF₄ micropolyhedra, K₂YbF₅ microprisms, microrods and microspheres have been successfully synthesized by simply tuning the molar ratio of KF to Yb³⁺via a facile and general solution-based route. The influence of the KF dosage on the phase and morphology evolution of potassium ytterbium fluorides has been systematically investigated and discussed. And the mechanism about how the KF/Yb³⁺ molar ratio influences the anisotropic growth and the phase and morphology evolution was proposed. Taking K₂YbF₅ microrods as an example, the possible formation mechanism was presented on the basis of XRD patterns and the corresponding SEM images of the intermediate products obtained at different reaction time intervals. Additionally, the upconversion luminescence properties of Er³⁺ ion (2 mol%)-doped potassium ytterbium fluorides with different crystalline phases and architectures were studied in detail. Importantly, this study may provide a great opportunity for the systematical study of the general synthesis and luminescence properties of potassium ytterbium fluorides with predictable crystal phases and well-defined morphologies, which can offer a reference for the precisely controlled synthesis of other rare earth fluoride compounds.