Tuning of photoluminescence intensity of europium doped sodium yttrium fluorides synthesized via hydrothermal route

Hydrothermal synthesis of pure, europium doped sodium yttrium fluoride (NaYF4: Eu3+) and NaYF4: Eu3+@NaGdF4 core–shell nanostructures by using trisodium citrate as chelating agent is reported. The control of nanostructure morphology as function of heating time intervals under same reaction condition at 180 °C has been achieved. The synthesized nanostructures were characterized by powder X-ray diffraction (PXRD), Rietveld refinenement, field emission electron microscopy, transmission electron microscopy, infrared spectroscopy, and energy dispersive X-ray spectroscopy. PXRD analysis reveals that all synthesized nanostructures have hexagonal phase without any impurity. Thermogravimetric analysis suggests appreciable thermal stability of synthesized lanthanide doped fluorides and core–shell nanostructures. Photoluminescence spectra of the as synthesized nanocomposites were investigated in details which indicate that the emission intensities are modulated by the morphology of nanostructures which in turn is regulated by varying heating time intervals.