Preparation and upconversion properties of Ba2ErF7 and Ba2ErF7:Yb3+ powders

Novel Ba2ErF7 and Yb3+-doped Ba2ErF7 powders were synthesized by a coprecipitation method. In Ba2ErF7 sample, abundant upconverted emission bands from violet to infrared region are observed under 980 nm excitation, whereas only green and red emissions are observed under 812 nm excitation. Under the two excitations, the luminescence decay curves of the green and red emissions are measured and the quenching behaviors of Yb3+ doping are also explored. It is found that a suitable Yb3+ concentration can efficiently enhance the intensity ratio of the blue and violet emissions to the green and red ones, which may be due to the competition between the energy transfer process from Er3+ to Yb3+ and the sensitizing process from Yb3+ to Er3+ in Ba2ErF7:Yb3+. This indicates that the Yb3+-doped Ba2ErF7 might be a good candidate for blue and violet upconversion phosphor.