| Long afterglow luminescent materials play a key role in our daily life,and it is widely used in various fields.Such as safety signage,bio-imaging systems and fluorescence probeand so on.In recent years,fluorescence detection technology based on biologically transparent window has developed rapidly and demand has been greatly increased,so it is required to generate broadband emission in the near infrared.Therefore,the advantages of transition metal ions with broadband near-infrared light emission and high quantum efficiency are even more obvious.Among them,Cr3+ion is a commonly used near-infrared(650-1000nm)long afterglow luminescent center ion.Cr3+ions 3d outer electrons are easily affected by the crystal field environment,so a matrix with rich defects can extremely prolong the decay time.In the gallogermanate(Zn-Ga-Ge-O)matrix,Cr3+ions(0.0615 nm)and Ga3+ions(0.062nm)have similar ionic radius and are easy to replace the Ga3+ions in a strong lattice field.So Cr3+ions play the role of the luminous center and result in 650-1000 nm range of near infrared light.The gallogermanate matrix has attracted much attention in recent years,because of its advantages of reasonable conductivity,high stability,low synthesis temperature and many defects.Such as Ge vacancy(VGe),oxygen vacancy(VO),Zn vacancy(VZn)and so on.However,the composition of Zn3Ga4GexO9+2x:Cr3+has not been reported.Therefore,the Zn3Ga4GexO9+2x:Cr3+luminescent materials are further explored in this paper.And its crystal structure,excitation spectrum,emission spectrum,afterglow attenuation curve and afterglow luminescence mechanism were analyzed in detail.The main work and conclusions are as follows:First,we carried out the matrix ratio experiment,and choose the best luminescence matrix.The results showed that the change of the Ge molar content has little effect on the main phase of the Zn3Ga4GexO9+2x:Cr3+(x=1,2,3,4,5)lattice.The shape and position ofexcitation and emission peak have not changed,only the intensity obviously change,and the intensity of Zn3Ga4GeO11:Cr3+was significantly better than that of other samples.In addition,the persistence luminescence time of all the samples is as long as 300 h,and the best afterglow properties is x=1.So Zn3Ga4GeO11:Cr3+is more potential in the practical value,also to lay the foundation for the later experimental research.In addition,we explored the sintering temperature and the molar content of Cr3+ions influence on the luminescence properties of samples.The results showed that the optimum sintering temperature of Zn3Ga4GeO11: Cr3+is 1200?.By changing the molar content of Cr3+ions,the Cr3+ions concentration quenching phenomenon is at x=0.04.But the afterglow intensity of the sample is the strongest at x=0.02.Considering the research of long afterglow luminescence properties,so choose the molar content of Cr3+ions is x=0.02.Further,we explored the alkali metal ions(Li+,Na+,K+)influence on the luminescence properties of Zn3Ga4GeO11:Cr3+samples.The experimental results showed that the luminescent performance of Na+ion doped Zn3Ga4GeO11:Cr3+phosphor is better.In addition,by changing the content of Na+ions,the afterglow intensity and duration of the samples can be adjusted,and the afterglow properties samples is the best at x=0.1.Finally,The transition metal ions(M=Mo?Mn?Nb?Ti?Zr?W?Ta?Fe?Ni)doped Zn3Ga4GeO11:0.01Cr3+,0.01 M and Zn3Ga4GeO11:0.02 M phosphors were explored.The results showed that the transition metal ions did not play a role in the luminescence center of the host lattice.But the afterglow luminescence intensity is enhanced of some transition metals doped Zn3Ga4GeO11:0.01Cr3+,0.01 M samples,and all the Zn3Ga4GeO11:0.02 M samples afterglow luminescence intensity is very weak. |
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