Tuning the crystalline phase and morphology of the YF3:Eu3+ microcrystals through fluoride source

Abstract

A series of Eu³⁺-doped pyridine functionalized YF₃ microcrystals were synthesized at low temperature (70 °C) using a simple colloidal route. The shape and phase of the YF₃ microcrystals were tuned using different fluoride sources (e.g. NaF, NaBF₄ and NH₄F). Cubic phase of the microcrystals with flower like morphology was achieved with NaF as fluoride source, while use of NaBF₄ and NH₄F led to the formation of orthorhombic phase with bundle and rice flake like morphology, respectively. This difference in the morphology and phase is reflected in their optical properties as well. A mechanism has been proposed for the formation of different morphology of YF₃ microcrystals. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrum (FTIR), photoluminescence (PL) and lifetime measurements were used to characterize the structural and optical properties of microcrystals.