Study On Preparation And Modification Of Rare Earth Doped Gadolinium Borate

With the development of plasma display panel（PDP）,requirements of high-quality phosphors gradually increase.Phosphors based on gadolinium borate have better stabilities,higher light intensity and emission efficiency than silicate or aluminate based phosphors.Nowadays,phosphors based on gadolinium borate have become the focus used in PDP field.Research indicates that fluorescence properties of phosphors doped with non-rare-earth metal ion improve remarkablely.Hydrothermal method with mild reaction condition and good crystallization properties has recently become a new method for the synthesis of rare earth phosphor powder.In this work,GdBO₃:Tb³⁺ and GdBO₃:Eu³⁺ phosphors were both prepared by hydrothermal method.On the basis of the best molar ratio of Gd³⁺ and Tb³⁺(Eu³⁺),non-rare-earth metal ion Mn⁺(Na⁺、K⁺、Mg²⁺、Al³⁺)were doped.Emission intensity,quantum efficiency,structural properties were studied by fluorescence spectrophotometer,field emission scanning electron microscopy and X-ray diffractometer.Main results achieved in this work were listed as follows.GdBO₃:Tb³⁺ phosphors prepared by hydrothermal method have a hexagonal structure with good crystallinity.When the concentration ratio of Gd³⁺ and Tb³⁺ is 20:1,emission intensity and quantum efficiency of phosphors both reach the maximum.After doping with suitable amout of Na⁺,K⁺ or Mg²⁺,emission intensity of phosphors has the trend to increase.When the doping ratio of Gd³⁺:Tb³⁺:Na+ is 20:1:1,emission intensity and quantum efficiency increase by 41.5% and 23.0%,repectively.When the doping ratio of Gd³⁺:Tb³⁺:K+ is 20:1:5,emission intensity and quantum efficiency increase by 78.6% and 21.8%,respectively.And when the doping ratio of Gd³⁺:Tb³⁺:Mg²⁺ is 20:1:2,emission intensity and quantum efficiency increase by 38.9% and 39.8%,respectively.What’s more,after doping Al³⁺,there are nearly no peaks,showing irregular granules on its surface and decreasing the fluorescence property.When the doping ratio of Gd³⁺:Tb³⁺:Al³⁺ is 20:1:0.5,the emission intensity and quantum efficiency decrease to 33.7% and 54.3% respectively compared with pristine GdBO₃:Tb³⁺ phosphors.GdBO₃:Eu³⁺ phosphors prepared by hydrothermal method have a hexagonal structure with good crystallinity.When concentration ratio of Gd³⁺:Eu³⁺ is 20:1,emission intensity and quantum efficiency of phosphors both reach the maximum.After doping with suitable amout of K+,emission intensity of phosphors has the trend to increase.When the doping ratio of Gd³⁺:Eu³⁺:K+ is 20:1:2,emission intensity and quantum efficiency increase by 34.9% and 21.6%,respectively.After doping with suitable amout of Na+,Mg²⁺ or Al³⁺,emission intensity of phosphors has the trend to decrease.When the doping ratio of Gd³⁺:Eu³⁺:Na+ is 20:1:1,emission intensity and quantum efficiency decrease about 44.0% and 37.6%,respectively.When the doping ratio of Gd³⁺:Eu³⁺:Mg²⁺ is 20:1:1,emission intensity and quantum efficiency decrease about 15.9% and 16.7%,respectively.And when the doping ratio of Gd³⁺:Eu³⁺:Al³⁺ is 20:1:0.5,emission intensity and quantum efficiency decrease about 71.6% and 56.8%,respectively.