Study On Doping Modification Of Zinc Gallate Based Near-infrared Persistent Luminescent Materials And Their Luminescence Properties

Persistent luminescence materials,also known as long afterglow luminescence materials,are a class of materials that can absorb energy?such as visible light,ultraviolet light,X-ray,etc.?,and emit light for a long time after the stoppage of excitation.Research on persistent luminescence materials dates back to the mid-20 th century.Traditional persistent luminescence materials usually emit yellow,green or blue light.Currently,rare-earth doped phosphors,especially green-emitting SrAl₂O₄:(Eu²⁺,Dy³⁺),are well developed and widely used as persistent luminescence materials.In recent years,near-infrared persistent luminescence materials have attracted much attention,since they can serve as a type of probe to show pathological changes of biological tissue.Therefore,they have a great potential for applications in optical bio-imaging and medical diagnoses.The purpose of this paper is to synthesize a kind of near-infrared persistent luminescence materials with high emission intensity and long afterglow time.The main contents of the paper include the following points:With ZnO,Ga₂O₃ and Cr₂O₃ as raw materials,ZnGa₂O doped with different concentrations of Cr₂O₃ were prepared by high temperature solid-state reaction.The crystal structure,PL properties and afterglow properties of the samples were characterized by X-ray diffraction?XRD?,Photoluminescence spectroscopy?PL?and Thermoluminescence spectra?TL?.The results showed that a small amount of Cr³⁺doping had no effect on the crystal structure of ZnGa₂O₄.Under the excitation of the external light,the samples emited red and near infrared light in the wavelength range of 650nm-720 nm.Appropriate concentration of Cr³⁺doping had a significant effect on the luminescence intensity of the sample,excessive Cr³⁺doping would cause concentration quenching of the sample emission.When Cr³⁺doping amount is 0.1%mol,the longest afterglow duration was obtained.Zn_1+xGa_2-2x?Ge/Sn?_xO₄?0?x?0.5?samples with 0.1%mol Cr³⁺doping were prepared by high temperature solid-state reaction using ZnO,Ga₂O₃,Cr₂O₃,GeO₂ and SnO₂ as raw materials.Similarly,we analyzed the crystal structure,PL properties and afterglow properties of the samples by X-ray diffraction?XRD?,Photoluminescence spectroscopy?PL?and Thermoluminescencespectra?TL?,respectively.The results showed that there was no obvious change in the crystal structure of co-doped Zn_1+xGa_2-2x?Ge/Sn?_xO₄ within a large range of Ge⁴⁺/Sn⁴⁺doping ratio,but the diffraction peak exhibited a slight shift,which suggested that Ge⁴⁺and Sn⁴⁺ions were successfully replaced Ga³⁺ions in the crystal lattice of the spinel ZnGa₂O₄.The emission spectrum of Ge⁴⁺/Sn⁴⁺doped samples changed obviously.The peak positions of the thermoluminescence spectra shifted to the high temperature.And the afterglow duration of the samples was significantly improved with Ge⁴⁺/Sn⁴⁺doping.Zn_1.1Ga_1.8Sn_0.1O₄:0.1%molCr³⁺,x%mol Bi³⁺?x=0.1,0.5,1,2?with different doping concentrations of Bi³⁺ions were prepared by high temperature solid state reaction.The characterization results showed that an appropriate concentration of Bi³⁺doping in the sample significantly increased the emission intensity.The afterglow duration of the samples prolonged with the increase of Bi³⁺doping concentration,which indicates that the Bi³⁺ion doping samples plays an important role in improving the light emission and afterglow time of Zn_1.1Ga_1.8Sn_0.1O₄:0.1%molCr³⁺samples.