Preparation And Luminescence Properties Of Manganese Doped Zinc Silicate Based On Mesoporous Silica

Inorganic phosphors display extensive applications in light emitting diodes,field emission displays,and plasma display panels.Silicate has the advantages of simple preparation,abundant raw materials,strong adaptability,crystal structure stability,thermal stability,and chemically stability,which is an ideal matrix material for many luminescent ions such as Mn²⁺,Eu³⁺,and Ce³⁺.Exploration of special morphologies and novel structures of silicates is an effective way to modulate and improve the luminescence properties.In this paper,Mn-doped zinc silicate luminescent materials were prepared using mesoporous silica as a template.The effects of structure,morphology,and alkali metal co-doped ions on luminescence properties of Mn²⁺ions were studied.The contents are as follows:1.Manganese-doped zinc silicate luminescent materialThe ordered mesoporous Mn-doped?-Zn₂SiO₄-SiO₂ composites were synthesized by solid-state reaction at 800 ^oC and mesoporous silica was used as the template and silicon source.The temperature at which manganese-doped?-Zn₂SiO₄is formed is much lower than the conventional solid-phase reaction temperature,which is due to the porous structure and large specific surface area of mesoporous silica.The Mn-doped?-Zn₂SiO₄ are dispersed in the mesoporous silica framework.The mesoporous silica supports the mesoporous structure,inhibits the phase transformation of?-to?-Zn₂Si O₄,and improves the stability of the composites.The excitation spectrum of the composite shows the zinc silicate absorbs band at 210 nm and the charge transfer band is at 245 nm.For the Mn-doped?-Zn₂SiO₄-SiO₂composites,UV emission attributed to silica occurs at 390 nm and a strong yellow light appears at about 575 nm due to the radiative transition of Mn²⁺from ⁴T₁ to ⁶A₁.At a concentration of 0.08,there was no significant concentration quenching,demonstrating that Mn²⁺is uniformly doped in the composite.This method has the important advantage of reducing the reaction temperature,easy doping and preventing concentration quenching.2.Barium,manganese co-doped light-emitting materialsBarium and manganese-doped zinc silicates was prepared under hydrothermal treatment by mesoporous template route employing mesoporous silica as an active template.The sample particles are rod-like morphology and single crystalline with a mean diameter of⁴0nm and a mean length of⁴50 nm,which similar to the morphology of the template mesoporous silica.The individual rods assemble into bundle-like hierarchical structure along the channels of the mesoporous silica.When barium ions together with manganese ions are co-doped in zinc silicate,the green emission at 522 nm display a significant enhancement,especially for the sample with the barium doping concentration of 0.08,the luminescence intensity reaches the maximum value,which indicates that an energy transfer from barium to manganese ions takes place.With further increasing barium concentration from 0.08 to 0.10,due to the radius of barium ion is much larger than zinc ion,the recombination between the defects related to barium and the excitation states of the manganese dominates accompanying non-radiative transitions which can reduce the emission efficiency.3.Lead,manganese co-doped light-emitting materialsManganese ions and lead ions co-doped Zn₂Si O₄ has been prepared by hydrothermal method,with mesoporous silica was used as a template and as a silicon source.The luminescence properties of the samples have been investigated.All the green emission peaks at 520 nm correspond to the electronic transitions from the ⁴T₁to ⁶A₁ level of manganese ions.From excitation and emission spectral analylis,an enhanced luminescent characteristic of manganese ions in green spectral zones has been observed,due to the energy transfer from the lead ion to the manganese ion.The relative intensities of the peaks show a dependence on the concentration of the lead ion,when the lead doping concentration was 0.04,the corresponding peak intensity reaches the highest.With further increasing lead concentration from 0.04 to 0.10,the emission intensity decreases due to the concentration quenching.The results of the study indicate that mesoporous silica with mesoporous structure can effectively reduce the reaction temperature.The large specific surface area of mesoporous silica enables uniform doping of ions,resulting in improved luminescence properties.Therefore,luminescent material prepared using mesoporous silica as a template and a silicon source has excellent luminescence properties.Through ion co-doping,an energy transfer from the barium and lead to the manganese ion occurred,and the luminescence performance of the manganese ion is improved.