White up-conversion emission in Ba(MoO4)0.5(WO4)0.5:Yb3+,Ho3+,Tm3+ nano-phosphor

The nanophosphors of Ba(MoO4)0.5(WO4)0.5:Yb3+,Ho3+,Tm3+ with the CIE coordinates located in the white light region were hydrothermally synthesized. Ba(MoO4)0.5(WO4)0.5:Yb3+,Ho3+,Tm3+ X-ray diffraction (XRD) belong to the tetragonal crystal system, and both the scanning electron microscope (SEM) measurements and the Scherrer׳s equation calculations indicate that the size of these nanophosphors should be in the range of 35 nm-50 nm. Under the excitation at 980 nm laser, the emission peaks at 477 nm (blue), 546 nm (green) and 652 nm (red) should be attributed to the transitions of 1G4→3H6 (Tm3+), 5F4/5S2→5I8 (Ho3+) and 5F5→5I8 (Ho3+), 1G4→3F4 (Tm3+), respectively.