Template-free synthesis and photoluminescent properties of Sr2YF7:Eu3+ hollow polyhedrons-assembled hierarchical microspheres

A simple one-step hydrothermal strategy has been developed to fabricate Sr2YF7 hierarchical microspheres employing NH4BF4 as fluoride source. The crystalline phase and morphologies of the products were characterized by XRD, TEM and SEM. The XRD results showed that the as-prepared samples were tetragonal phased Sr2YF7 with high crystallinity. SEM and TEM observation indicated that the as-synthesized hierarchical microspheres with average size of about 2 mu m were assembled by hollow polyhedrons. N-2 adsorption-desorption measurements revealed that the BET specific surface area of the typical Sr2YF7 hierarchical microspheres is up to 111.4 m(2)/g. The size and morphology of the products could be effectively controlled by adjusting the reaction times. Furthermore, the photoluminescence of hierarchical Sr2YF7:Eu3+ microspheres and hollow polyhedrons were measured, the result showed that PL intensity and decay time were sensitive to the morphology of the product. (C) 2018 Elsevier B.V. All rights reserved.