Controllable synthesis of polyhedral YF₃ microcrystals via a potassium sodium tartrate-assisted hydrothermal route

In the present paper, we reported the successful synthesis of polyhedral yttrium trifluoride (YF₃) microcrystals via a simple hydrothermal route, employing yttrium oxide (Y₂O₃ 99.99%), ammonium fluoride (NH₄F) as the starting reactants and potassium sodium tartrate (C₄H₄O₆KNa·4H₂O) as the structure-directing reagent. The reaction was carried out at 150°C for 16 h. The phase and morphology of the product were characterized by means of powder X-ray diffraction (XRD), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), and field emission scanning electron microscopy (SEM). The research results indicated that the pH and K⁺ ions in the system played crucial roles in the formation of polyhedral YF ₃ microcrystals. Some factors influencing the morphology of YF ₃ crystals were investigated, including the reaction temperature, time, and the amounts of initial HNO₃, NH₄F and C ₄H₄O₆KNa·4H₂O. A possible growth mechanism of polyhedral YF₃ microcrystals is discussed.