The Study Of Luminescence Properties And Mechanisms Of Up-conversion Materials With Highly Blue And Green Up-conversion Efficiency

In this paper, the author firstly introduces in detail the fundamental theories about up-conversion research and several primary problems. Then shows his work results done for master degree. By adopting single doped, co-doped or triple-doped ways after adjusting the ingredients of host materials, the author has obtained several up-conversion materials with highly blue and green up-conversion efficiency as well as characteristic luminescence lines and peculiar relations of ratio of luminescence intensities. His experimental results have particularly great importance in the search of blue and green laser and the application of up-conversion materials to identification of securities or Guard against Forge. The main contents and important results of this paper are as following:Strong blue cooperative up-conversion luminescence is observed in various host materials single doped Yb3+ ions with naked eyes at room temperature under 980nm excitation. Moreover there exist rich emission lines and peculiar ratio of luminescence intensity in all samples.Intense green and blue up-converted luminescence is observed in Yb3+-Ho3+ co-doped PbF2-ZnF2 based materials with 930 nm diode light excitation at room temperature. It is found that with the increase of Ho3+ doped concentration, the highest luminescence peaks at the blue band shift towards long wavelength. Accordingly, we postulated that there exist energy transfer between Yb3+ and Ho3+ ions and cooperative up-conversion between Yb3+ ions in Yb3+-Ho3+ co-doped oxy-f luoride.In Er3+-Yb3+-Tm3+ triple-doped CdF2:PbF2-based glass, we obtained intense blue (480nm) and green (545nm) up-conversionluminescence as well as infrared (800nm), red (645nm)and violet (407nm) luminescence under 980nm excitation. With the addition of Tm3+ions, compared with that of the sample co-doped Yb3+-Er3+, the intensity of 480nm blue Luminescence is relatively enhanced by more than 30 times. Log-Log plot of the luminescence intensity versus pump power show that 480nm Luminescence emission is induced by the cooperative up-conversion between two Yb3+ ions.Er3+ doped ZnF2 -based phosphor exhibit intense red emission upon continuous wave excitation around 980 nm and its ratio of red and green luminescence intensities approximates to 21:1. It is interesting that with the increase of Yb3+ doped concentration, the ratio of red and green luminescence intensities decrease contrary to the results of references. It is estimated that those peculiarly experimental phenomena owe greatly to intense energy transfer processes among Er3+- Er3+ clusters and cooperative up-conversion between two Yb3+ ions.An Er3+/Yb3+ co-doped PbF2 thin film was prepared by pulsed laser deposition (PLD). With the infrared excitation, intense green luminescence was observed at room temperature.