olvothermal synthesis and luminescence properties of NaYF_4:Ln~(3+) (Eu~(3+), Tb~(3+), Yb~(3+)/Er~(3+)) nano- and microstructures

摘要

NaYF_4 and NaYF_4 (Eu~(3+) Tb~(3+), Yb~(3+)/Er~(3+)) nano- and microstructures were successfully synthesized through a facile and effective polyol-mediated route with ethylene glycol (EG) as solvent. The factors including the molar ratio of F~-/Y~(3+) reaction temperature and reaction time were well studied in the influences on size, morphology and phase transition of samples. The experimental results indicate that the F~-/Y~(3+) ratio and reaction temperature play key roles in crystal phase and morphology of the product. Higher molar ratio of F~-/Y(3+) and higher temperature as well as longer reaction time facilitate α cubic structure-to-β hexagonal structure phase transition, which behaves as a dissolution-recrystallization transformation process. Pho-toluminescence measurements demonstrated that the as-prepared β-NaYF_4 is one good up- and down-conversion luminescent host material.