Facile precipitation synthesis of green-emitting BaY2F8:Yb3+, Ho3+ upconverting phosphor

Monoclinic phase of BaY2F8:0.2Yb(3+), xHo(3+) (x = 0.005, 0.01, 0.02, 0.05 and 0.1 mol) and BaY2F8:yYb(3+), 0.02Ho(3+) (y = 0.01, 0.02, 0.05, 0.1 and 0.2 mol) phosphors were prepared by a facile precipitation method. Rietveld analysis was employed to carry out the structural refinement. The upconversion (UC) luminescence properties of BaY2F8:Yb3+, Ho3+ phosphor were investigated under near infra-red (NIR) excitation and the influence of dopant concentration on their spectra was also accessed. The possible UC processes and the energy transfer mechanisms between Yb3+ and Ho3+ were discussed on the basis of UC decay curves and the UC spectra obtained from a laser-pump power variation. The thermal stability of the BaY2F8:0.2Yb(3+), 0.02Ho(3+) phosphor was studied in the range of 30-300 degrees C. The color coordinates of the phosphor were located in the green region with very high color purity.