Synthesis and multicolor upconversion of Tm 3+/Er 3+/Yb 3+ doped Na (Y 1.5Na 0.5) F 6 single-crystal nanorods

Abstract

Er 3+/Tm 3+/Yb 3+ tri-doped Na (Y 1.5Na 0.5) F 6 single-crystal nanorods were synthesized by a facile hydrothermal treatment method. The tri-doped sample was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). The sample showed a pure hexagonal phase structure with space group P6 3/ m and nanorod morphology. Under 980 nm excitation, intense red, green and blue upconversion emissions were observed. The red and green upconversion are consistent with 4F 9/2 → 4I 15/2 and 2H 11/2, 4S 3/2 → 4I 15/2 transition of Er 3+, respectively, while the blue upconversion originates from 1G 4 → 3H 6 transition of Tm 3+. Moreover, the Er 3+/Tm 3+/Yb 3+ tri-doped Na (Y 1.5Na 0.5) F 6 nanorods exhibit strong red and green emission which is ascribed to the sensitization of Tm 3+ to Er 3+. The energy transfer upconversion mechanisms for the fluorescent intensity are also discussed.