Studies On The Preparation And Near-Infrared Luminescence Properties Of Inorganic Phosphors Doped Rare-earth Ions

Recently, there is considerable interest in near-infrared luminescence of Er³⁺, Nd³⁺ and otherlanthanide ions, due to their many advantages of strong penetrability, narrow linewidth and freeof background for the potential applications in optical communications, laser, medicine andfluoroimmunoassay. Various NIR luminescent materials doped rare-earth ions have been studied.In this paper, based on two requirements of the fluoroimmunoassay labels which were theregular morphology and strong NIR emission, the synthesis and light emission properties ofseveral Ianthanide-doped NIR luminescent materials were discussed. The conclusions and resultswere summarized as follows:NaLa(WO₄)₂:Ln³⁺(Ln=Er, Nd) powders were synthesized by a mild hydrothermal methodand Well-dispersed particles with nearly spherical morphology were obtained. The influences toNIR luminescence of sintered temperature, time and initial pH on the morphology weresystematically investigated. The particles with spherical morphology and stronger NIRluminescence were obtained for potential application to luminescent label.YAG:Ce, Er powder samples were prepared by a co-precipitation method and solid-statemethod. It was found near-infrared luminescence of Er³⁺ in YAG could be very efficientlysensitized with co-doped Ce³⁺, and the NIR emission intensity is almost 1000 times of that ofYAG:Er when excited with a 476nm of an argon laser. The energy transfer mechanism from Ce³⁺to Er³⁺ was proposed. The influences of sintered temperature and the dopant concentration wereinvestigated, and the strongest NIR emission of YAG:Ce, Er samples was obtained when sinteredat 1500℃for 4h and doped with 5-6% Ce and 15% Er. In addition, it was investigated how toinfluence the Er³⁺-luminescence properties in (Y_xGd_1-x)₃Al₅O₁₂ samples with co-doped Ce³⁺.SrxBa_2-xSiO₄:Eu, Nd samples were synthesized by a solid-state method. It also was found thatenergy transfer from Eu²⁺ to Nd³⁺ in Sr_xBa_2-xSiO₄:Eu, Nd samples, and the mechanism, wasdiscussed simply.