Preparation And Investigation Of Novel X-Ray Persistent Luminescence Materials

With the recent emergence of biomedical imaging technology,the activities and responses of cells marked with optical signals in small living animals can be non-invasively monitored in real time.Biological imaging material mainly includes quantum dots and nano-upconversion material.However,due to the poor ability of biological imaging to penetrate tissue,it can only be applied to body surface tissue.For its good penetrability through tissue,X-ray is an ideal light source for in vivo biological imaging.Nevertheless,in view of its harmfulness to human body,the radiation dose of X-Ray should not be too high,so the material of afterglow excited by X-ray is the ideal one for biological imaging.The research in this paper is to find a suitable material to achieve long-term afterglow emission with low X-ray radiation.In this paper,fluoride host luminescence material was prepared by high temperature solid state method and hydrothermal method respectively.The structures and the morphologies of the as-synthesized samples were investigated by XRD,SEM and EDS.Their luminescence properties were investigated by photoluminescence spectra.The properties of afterglow and thermo luminescence were investigated by faint light photometer and TL dosimeter respectively.The main contents were summarized as follows:?1?The NaYF₄:Pr³⁺ phosphor was prepared by solid state method.The influence of the temperature,raw materials and concentration of fluoride source on the crystal phase of NaYF₄ was explored.A series of ????-NaYF₄:xPr³⁺ were prepared in this paper.The X-Ray diffraction of ????-NaYF₄:xPr³⁺ were investigated,and the curves of emission spectra excited by X-Ray,afterglow decay,and thermo luminescence were obtained.The optimum doping concentration of Pr³⁺ was 3% in the ?-NaYF₄ while 1% in the ?-NaYF₄.Pr³⁺ had a stronger luminescence and longer afterglow in ?-NaYF₄ than in ?-NaYF₄.Finally,Mg2+ was doped into ?-NaYF₄:1% Pr³⁺ and then the sample had a stronger luminescence and longer afterglow.?2?The NaYF₄:Pr³⁺ phosphor was prepared by hydrothermal method.The effects of concentration of fluoride source and the value of p H on the crystal phase and morphologies of NaYF₄ were explored.The XRD,SEM and EDS of NaYF₄: Pr³⁺ was investigated,and the curves of emission spectra excited by X-Ray,afterglow decay,and thermo luminescence were obtained.High concentration of fluoride source was helpful for generating rod-shaped particles and the higher pH value,the smaller particles.With pH=5 and yttrium fluoride ratio of 1:8,the sample had the strongest luminescence and thermo-luminescence,and the longest afterglow.?3?The NaYF₄:Pr³⁺ phosphor was prepared by pyrolysis method.The size of the sample particle for pure phase of NaYF₄ was 30-40 nm.The KYF₄:Pr³⁺ phosphor was prepared by hydrothermal method.The XRD of KYF₄: Pr³⁺ was investigated,and the emission curves of spectra excited by X-Ray as well as afterglow decay and thermo luminescence were obtained.The size of the sample particle for pure phase of KYF₄ was 30-40 nm.Under the excitation of X-ray,the sample had visible luminescence and afterglow.