Hydrothermal synthesis of the intense green photoluminescence of hexagonal phase NaYF4:Yb3+/Er3+ microcrystals

Abstract

Hexagonal phase NaYF4:Yb3+ 20mol%/Er3+ 1mol% microcrystals that exhibit intense green emission were successfully synthesized via a facile hydrothermal method. The factors including the NaF/Ln (Ln=Y+Yb+Er) molar ratio, pH value of the precursor solution, and the ethylenediaminetetraacetic acid (EDTA)/Ln molar ratio, were well studied in the influences on the crystal structures, morphologies, and sizes of final products. The experimental results indicate that the NaF/Ln ratio and pH value play key roles in crystal structure and morphology of the product. Photoluminescence measurements demonstrate that the relative up-conversion photoluminescence intensity of as-prepared products strongly depends on the crystal structures, crystallization degrees, morphologies, and sizes.