Key Words:Upconversion; Crystal transition control; Solvothermal synthesis method
Abstract:Hexagonal uptonversion microcrystals of beta-NaY4 were prepared through a simple, one-step, rapid, template-free and mild solvothermal synthesis method. Addition of Na2HPO4 influenced crystal transition from the cubic phase to the hexagonal phase. Results showed that the phase (cubic or hexagonal) and upconversion emission intensity of NaYF4 can be rationally tuned by introducing inorganic dopant ions to achieve a precisely defined molar ratio of Na2HPO4 to Ln(3+). SEM observations and XRD analyses helped identify fundamental considerations for crystal transition control during upconversion of NaYF4 particles. Results also showed that Na2HPO4 short-ened the reaction time (3 h) of cubic-to-hexagonal crystal transition and significantly reduced the reaction temperature (200 degrees C) during the preparation of hexagonal phase upconversion microcrystals. (C) 2015 Elsevier Ltd. All rights reserved.
Volume:88
Translation or Not:no