| Rare earth ions doped luminescent material exhibits many excellent properties, such as strong absorption ability, high color purity, and colorful hue, wild range of emission wavelength, stable physics and chemistry property. As a result, this kind of material has a wide range of application in many fields such as illumination, display, laser medium, fiber amplifier, optical communication, energy storage and so on. However, the emission efficiency is relative low because of their special4f electronic transition structure. Glass has many advantages as a host for luminescence materials:high transparency, low cost, easy processing and high luminescent efficiency etc. In addition, due to the special structure of glass-short-range order and and long-range disorder, high concentration of rare earth ions can be doped in glass. As a result, the halo effect can be avoided. Based on these, rare earth ions doped glass is an important material applied in photoelectric field widely. Therefore, it has important research significance in studying optical properties of rare earth ions doped glass, and how to improve luminescent efficiency of rare earth ions doped in glass has an important theoretical value in basic research and device project.Experiments demonstrated that rare earth ions are placed in the gaps outside the glass network in inorganic glass. They are connected with anion group mainly through ionic bonds. To a large extent, the luminescent properties of activators and their light absorption ability have relationships with networking formation anion group. Besides, the modifiers such as alkaline earth metal ions have a certain impact in the luminescent properties of activators. Therefore, the optical properties of rare earth ions can be regulated by the adjustment of glass structure. The main research contents are as follows:In this work, rare earth ions doped borate glasses are prepared. We discussed the influence of the glass structure on the rare earth luminescence by changing the borate glasses. Borate glass is famous for both low melting point and special structure units. The structure transition between [BO3] units and [BO4] units is existed in the glass when appropriate alkali metal ions or alkali-earth metal ions are doped in the B2O3glasses. This change will affect the emission of rare earth ions deeply. Herein, with variation of network forming B2O3and network medium Al2O3, the luminescent properties of Eu3+doped B2O3-Al2O3-Na2O glasses is investigated. The results indicate that with increasing of B2O3/Al2O3concentration, Eu3+ions are reduced to the divalent and the blue emission of Eu2+is observed in the air condition. Moreover, with increase of B2O3/Al2O3, the Eu+emission is enhanced evidently and the mutated growth of Eu2+luminescence happened in the higher Al3+ions doped samples. The structure detection revealed that the glass structure is turned from [BO4] units to the [BO3] units with increasing of B2O3/Al2O3concentration, which means the pentaborate groups, tetraborate groups consist of [BO3] and [BO4] units are turned to the low polymeric groups such as boroxol rings, triborate and orthoborate groups composed by the main [BO3] units. Moreover, during the decomposition process, low polymerized units with large negative charges are reacted with neighboring Eu3+ions leading to the Eu+ions reduction effect. It is therefore that the luminescence of rare earth ions can be controlled by the alternation of the glass structure induced by the varied composition.Owing to the good work of the plasma resonance, the metak nanoparticles in the glass matrix is available to influence on the luminescence of rare earth ions. However, the unclear problems are existed such as the formation mechanism of the technical nanoparticles in the host, the types of the metal ions and their rule effect on the rare earth ions emission. Therefore, The occurance state of the metal ions in the glass network is investigated by change of the structure of the borate glasses. And the avaible control on the rare earth ions luminescence is expected to be relized through the study of the energy transfer interaction between metal ions or nanoparticles and rare earth ions. It is found that the type of the noble silver is changed from their high polymeric state to the lower ones with transformation of [BO4] to [BO3] units. Namely, the luminesce intensity of Ag+and Ag aggregates is increased and the the precipitation ability of the Ag nanoparticles goes down. Fortunately, the variation is contributed for the emission of the doped rare earth ions. Energy transfer is proceeding from the low polymeric Ag species to the Eu3+ions emission efficiency. It is believed that the galss structure can be changed to control the type of the metal ions and then improve the luminescent properties of the rare earth ions in the glass.Accordingly, the variation of the glass component can selectively control the micro structure of the glasses and furthering to adjust the luminescence of the rare earth ions. In this paper, the external field mode is employed by the femtosecond laser irradiation into the glass to study their effect on the glass structure, including the interaction of the induced structure and the rare earth ions emission. The results indicates that part of doped Sm3+ions is reduced to the Sm2+in the laser focus where the micro structure is existed induced by the irradiation effect because of the multiphoton ionization. Not only that, but the luminescent efficiency is enhanced after the halide ions F is substituted by the Cl and Br ions with femtosecond laser effect. Even the significant enhancement of Sm2+luminescence is observed in the high halide ions Cl/Br doped samples. Structure anaylisis by TEM measurement indicates that the nanophase containing halide ions Cl or Br is precipited from the glass matrix and Sm3+is selectively incooperated into the nanophase by the femtosecond laser irradiatin effect. Besides, the reduction ability in Br substituted samples is stronger than Cl substituted galsses and both stronger than fluorate galsses. And the electronegativity effect is the proposed for the phenomenon. The lower of the electronegativity value, the ability of drawing electrons is stronger and the reduction ability is higher. Therefore, the external effect on the galss structure is another efficient method for the control of rare earth ions luminescence properties. |
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