Research On The Synthesis And Luminescence Properties Of Mn⁴⁺ And Mn²⁺ Doped Complex Oxides

In this paper, Mn⁴⁺and Mn²⁺doped aluminates and germanates,have been synthesized using solid-state reaction method and combustionmethod. The composition, morphology and luminescence properties ofsamples have been investigated by XRD, SEM, excitation and emissionspectra and decay. The influence of composition, synthetic methods andconditions （temperature, time, atmosphere, co-solvent, etc.）, the type ofdopant ions, and the concentration of dopant ions on the excitationwavelength, emission wavelength, intensity, fluorescence decay, andluminescence mechanism have been studied. The nonradiative relaxationof the activation ions has been decreased and the mechanism ofimproving the photoluminescence efficiency of luminescence materialshas been investigated. Specific conclusions are as follows:（1）. Red phosphor CaAl⁴⁺12O19:Mn（CAO:Mn） has been synthesizedby combustion method and solid sate chemistry, respectively. Theluminescence properties and morphologies have been optimized by addition of mixture of urea and citric acid, and fluorides. The emissionintensity of the phosphor has been increased by8times with addition of50mol%MgF²⁺2of Ca.（2）. Green and red photoluminescence （PL） is obtained frommanganese activated phosphor CaAl₁₂O₁₉（CAO），which only emits redlight without co-doping of other ions, through co-doping of trivalent ionsin air such as Bi³⁺，La³⁺，Sm³⁺，Nd³⁺，Tm³⁺and Dy³⁺. The intensities ofthe green and red luminescence strongly depend on the co-dopingconcentration of the trivalent ions.（3）. A novel red phosphor CaAl⁴⁺4O7:Mnhas been synthesized bysolid state reaction at900oC. The optimal concentration of Mn⁴⁺is0.01%of Al3+. The emission intensity of the phosphor has been increasedthrough addition of fluorides.（4）. The luminescence intensity of green phosphor Zn₂GeO₄:Mn²⁺has been improved up to9and6times through mixing GeO₂and MgF₂into the composition, respectively. The emission of the optimizedphosphor has higher intensity and shows red shift compared to thecommercial green long lasting phosphor SrAl₂O₄:Eu³⁺, Dy³⁺.