Upconversion Emissions of Er~(3+)-doped Yb_2Ti_2O_7 Powders by Sol-gel Method

The 8 mol% Er3+-doped Yb2Ti2O7 powder,which was composed of single phase of Yb2Ti2O7,was prepared by sol-gel method.The green and red upconversion emissions of Er3+-doped Yb2Ti2O7 centered at about 524,548 and 660 nm were detected by a 980 nm semiconductor laser diode excitation.The intensities of green and red upconversion emissions(Igreen,Ired) increased with increasing the pump power of laser diode.The two-photon absorption upconversion process was involved in the green and red upconversion emissions.With increasing the temperature of Er3+-doped Yb2Ti2O7 powder,Igreen and Ired decreased with the ratio of Igreen/Ired increasing,while the intensity ratio of green upconversion emissions centered at about 524 and 548 nm(I524/I548) increased.The result implies that the Er3+-doped Yb2Ti2O7 powder with the change of green upconversion emissions depending on the temperature of powder has a potential application for optical high temperature sensor.