Solvothermal synthesis and luminescence properties of NaYF4:Ln3+ (Eu3+, Tb3+, Yb3+/Er3+) nano- and microstructures

Abstract 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. Photoluminescence measurements demonstrated that the as-prepared β-NaYF 4 is one good up- and down-conversion luminescent host material.