| Summary: | Novel single-source precursors based on sodium and lanthanide pentafluoropropionates have been developed for chemical solution deposition of NaLnF<sub>4</sub> thin films (Ln = Y, Yb, Er, Tm). A series of [Ln<sub>2</sub>(pfp)<sub>6</sub>Q<sub>n</sub>] (Q = H<sub>2</sub>O, diglyme) and mixed-metal NaLn(pfp)<sub>4</sub>Q<sub>n</sub> were synthesized and characterized by X-ray diffraction (XRD) and thermogravimetric analysis (TG-DTA). Thermal decomposition of individual Na(pfp) and Ln(pfp)<sub>3</sub> occurs at different temperatures while single-source NaLn(pfp)<sub>4</sub> decomposes with the transformation to NaLnF<sub>4</sub> in a single stage at 280 °C. Further crystallization of NaLnF<sub>4</sub> was studied by variable-temperature powder XRD, which shows two phase transformations from cubic NaLnF<sub>4</sub> to hexagonal NaLnF<sub>4</sub> at 310 °C and back to a high-temperature cubic phase at 560 °C. The thin films of NaY<sub>0.78</sub>Yb<sub>0.2</sub>Er<sub>0.02</sub>F<sub>4</sub> prepared by the dip-coating technique on Al<sub>2</sub>O<sub>3</sub> substrates showed intense up-converting luminescence in green and blue regions under 980 nm excitation.
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