Preparation and Luminescent Properties of Rare Earth Doped Gd2（WO4）3Phosphors
|School||Harbin Normal University|
|Course||Condensed Matter Physics|
|Keywords||Co-precipitation method Concentration quenching Energy transfer Up-conversion emission|
Rare earth ions have rich energy can be excited from the ultraviolet to the infrared. Thephysical and chemical properties of it are stability.It is often used in light-emitting materials,especially rare earth doped nanostructured luminescent materials. Its performance isexcellent and has a broad application prospects. Preparation and room temperature emissionof nanocrystalline Gd2（WO4）3：RE3+(RE=Eu3+、Eu3+-Sm3+、Er3+、Er3+-Yb3+) arestudied in this paper. The results and conclusions are as following:The nanocrystalline Gd2（WO4）3doped by Eu3+,Eu3+/Sm3+,Er3+,Er3+/Yb3+are preparedby co-precipitation method in this paper. changing the doping concentration of the rareearth ion. The X-ray diffraction spectrum of the sample showed that the diffraction peak ofthe sample with the JCPDS card#23-1076matches the base-centered monoclinic structurecompletely. Calculated by the Debye-Scherrer equation （Debye-Scherrer） Gd2（WO4）3:RE3+series of samples of the grain size of about40nm samples prepared nanoscaleparticles.Eu3+, Sm3+doped and codoped Gd2（WO4）3nanocrystalline are prepared by chemicalco-precipitation method, respectively. When Eu3+is doped, the emission of5D0→7F2is thegreatest. With the increase of doping concentration increased, When the mole fraction ofEu3+is20%, the luminescent intensity of Eu3+is the greatest. when the intensity of luminouscontinues to increase, the occurrence of the phenomenon of concentration quenching. Sm3+sensitized Eu3+in the samples Gd2（WO4）3:Eu3+-Sm3+. The sensitized effect of Sm3+to Eu3+was more obvious when the sample Gd2（WO4）3:Eu3+-Sm3+was excited by464nm light thanby395nm light. Doping Sm3+can realize the energy transfer from Sm3+to Eu3+, making theemission of5D0→7F2more strength. When the mole fraction of Sm3+was5%, theluminescent intensity of Gd2（WO4）3:Eu3+-Sm3+is the greatest,the light intensify will bedecreases when increasing. The transition of5D0→7F2was clearly observed under405nm or440nm excitation. Therefore, Eu3+and Sm3+codoped in the matrix Gd2（WO4）3greatlyexpanded the range of the wavelength of the excitation light source. The Er3+, Er3+/Yb3+doped nanocrystalline Gd2（WO4）3phosphors are prepared byco-precipitation method. The down conversion characteristic emission from the trivalentrare earth Er3+ in the samples were observed. The concentration quenching will occur whenthe concentration of doped Er3+ exceeds3mol%. The up conversion characteristic emissionwere observed. When Eu3+is doped, The up conversion characteristic emission is not good,but, Er3+/Yb3+co-doped, up conversion emission intensity greatly enhanced, the resultsshow that Yb3+ion had a good sensitization for Er3+ ion up conversion emission. When thedoping concentration of Yb3+is1%, mainly2H11/2→4I15/2level transition of Er3+4S3/2→4I15/2level transition will be strengthened.When the Yb3+doping concentration graduallyincreasing, the level transition of4S3/2→4I15/2is increased at the same time. Meanwhile thelaunching of Er3+/Yb3+co-doped upconversion green （540nm563nm band） is a two-photon process.