Half opened microtubes of NaYF4:Yb,Er synthesized in reverse microemulsion under solvothermal condition

NaYF4:Yb,Er micro/nanocrystals with different sizes and morphologies such as nanospheres, short flexural nanorods, and half opened microtubes, were synthesized in reverse microemulsion under solvothermal condition using the quaternary reverse microemulsion system, CTAB/1-butanol/cyclohexane/aqueous solution. The X-ray diffraction analysis confirmed that cubic phase NaYF4:Yb,Er can completely transform to hexagonal phase with increasing reaction time. The scanning electron microscope and transmission electron microscope images revealed that the morphology of the product can be tailored by varying the reaction time. A possible crystalline growth process of the NaYF4:Yb,Er micro/nanocrystals was discussed. The obtained half opened microtubes exhibited an intense green upconversion luminescence, which may be attractive in novel optoelectronic devices.