| The development status was reviewed and the luminescent material of ZnGa204,was studied in this paper. By using matal Ga as main raw material, HGa02 and β-Ga203 (purity>4N) were synthesized by wet-chemical method. The synthesis methods for ZnGa204, ZnGa2O4:Mn2+, ZnGa2O4:Eu3+ phosphors were studied based on the raw materials of HGa02 and β-Ga203, and the luminescent properties of the three phosphors were investigated.The crystal structure and the luminescence mechanism of the synthesized samples were studied and discussed by the results of XRD, TGA-DTA and luminescent properties.The results shows that the samples synthesized with HGaO2 at the synthesis temperature at 1200℃~ 1300℃ has higher fluorescence intensity than with β-Ga2O3 or a-Ga2O3.The excess Ga or Zn is soluble in ZnGa2O4 and don't affect the spinel lattic of ZnGa204. When Zn excess, the formula of ZnGa204 changed into Zn (Ga1-xZnx)2O4, this formula leaded to the increase O2- vacancy. When Ga excess, the formula of ZnGa2O4 changed into (Zn1-xGax) Ga2O4 , this formula leaded to the increase Zn2+ vacancy. ZnGa2O4 is a new n-semiconductor material, its lattic interval exist the vacancies and ions, belong to structure defect or crystal defect. The luminescence mechanism is similar the luminescence of semiconducter, with an optical band gap of 4. 4eV. ZnGa204 is a kind of self-activated luminescence material with two self-activated optical center, e. g. [Td (Ga-0) ] and [ (Ga-0) ], its excitation and emission spectrums are wider. In Zn/Ga<0. 60, the absorpton band at 248nm and the fluorescence band at 367nm which is originated from self-activation optical centers of the tetrahedral [Td(Ga-0) ] in the spinel lattic. In Zn/Ga>0.60, the absorpton and the fluorescence band at 270nm and 441nm which is originated from self-activation optical centers of the octahedral [0h(Ga-0)] inthe spinel lattic. The peak of excitation and emission shifted to longer wavelenth when Zn/Ga ratio between 0. 55 and 0.60.The green luminance of ZnGa204:Mn2+ was prepared by using HGa02, ZnO and Mn(Ac)2. The excess Ga at near the stoichiometric composition Zn (Ga1-xZnx)2O4, it does good to the luminancent properties of Zn (Ga1-xZnx) 204. When ZnGa204 was doped with Mn2+, its spinel structure is not changed, but the formula of ZnGa204 changed into (Zn1-x-yGaxMny) Ga204. ZnGa204:Mn2+ is "composite" luminescence material .As Mn/Ga is about 0.008, the fluorescence intensity of ZnGa204:Mn2+ is highest. Both the excitation spectra with a maximun at 270nm and the emission spectra with a maximun at 504nm are corresponding to 4T1-6A1 of Mn2+.The red luminance of ZnGa204:Eu3+ was prepared by using HGa02, ZnO and Eu203. The excess Zn at near the stoichiometric composition is helpful to the luminescent properties of Zn (Ga1-xZnx) 204.. When ZnGa204 was doped with Eu3+, its spinel structure is not changed, but the formula ZnGa204 changed into Zn (Ga1-x-yZnxEuy)2O4. ZnGa204 :Eu3+ is also a kind of activated type luminescence material .As En/Ga is about 0.03, the fluorescence intensity of ZnGa2O4: Eu3+ is highest. Its excitation peak is at 275nm, and emission peaks are at 445nm and 618nm. The former emission peak (at 445nm) is resulted from host lattic ZnGa204, and the latter (at 618nm) is corresponding to 5D0-7F2 of Eu3+.The synthesized blue luminescent powder of ZnGa204 and the green luminescent powder of ZnGa204 : Mn2+ showed better fluorescent intensity (even exceed to the testing range) and have practical value. The red luminescent powder of ZnGa2O4: Eu3+ is not ideal at the aspect of luminescent properties, and need further improve. |
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