The Synthesis Of Rare Earth Doped Scandium Oxide And Calcium Scandate Nanomaterials And The Study Of Their Up-conversion Luminescence Properties

Rare earth-doped up-conversion luminescent materials refer to a class of materials that absorb low-energy photons and emit high-energy photons.Because of its unique luminescence performance and potential application value,it is favored by majority of researchers.However,the current disadvantages of up-conversion fluorescence,such as low efficiency and weak intensity,limit its practical application.As we all know,there are many factors that affect the luminous intensity and efficiency of host materials.Generally,the types of host materials play a key role in up-conversion luminous intensity and efficiency.Therefore,it is very important to develop excellent host materials and improve their up-conversion efficiency and luminous intensity.Among the oxide materials,scandium oxide and calcium scandate have many outstanding properties,they not only have good chemical and thermal stability,but also have a strong crystal field.At the same time,the atomic distance between the two is relatively low.So they are a very excellent upconversion matrix material.Therefore,the scandium-based oxide Sc₂O₃ and Ca Sc₂O₄upconversion luminescent host materials are regarded as the research objects of this thesis.The new synthesis method was successfully used to prepare Sc₂O₃ and Ca Sc₂O₄ in a round-bottomed three-necked flask by solvothermal method,and the luminescence characteristics and luminescence mechanism of the samples were studied.The research content and results of this paper are as follows:The first part of this paper is the successful synthesis of sub-nanoscale Sc₂O₃:Yb,Er upconversion nanoparticles(UCNPs)below 10 nm by solvothermal synthesis in a three-necked round bottom flask.X-ray diffraction(XRD)indicated that the prepared UCNPs have a cubic structure.Transmission electron microscopy(TEM)results show that the prepared nanoparticles have a relatively uniform size and a spherical shape with relatively high crystallinity.The average size of spherical UCNPs can be controlled within3 nm.In addition,the sample showed stronger red and green upconversion luminescence than the Sc₂O₃:Yb,Er nanostructures prepared by the two-phase solvothermal method.In addition,Fourier transform infrared spectroscopy(FTIR)and decay curves show that the surface groups of the ultra-small Sc₂O₃:Yb,Er UCNPs are reduced,and the decay time of Er³⁺ions becomes longer.The results show that Sc₂O₃:Yb,Er UCNPs are potential oxide materials,with smaller size and strong upconversion luminescence,which may be suitable for biological applications.In the second part of the thesis,Ca Sc₂O₄:Yb,Er upconversion nanoparticles were successfully prepared by solvothermal method in a three-necked round bottom flask.XRD shows that the synthesized Ca Sc₂O₄:Yb,Er has an orthogonal Ca Fe O₄ structure.TEM shows that the Ca Sc₂O₄:Yb,Er prepared by this new method is uniform,good monodispersity,and spherical UCNPs with a particle size of about 30 nm.And through up-conversion fluorescence spectrogram,color coordinate(CIE)and other characterizations,the prepared samples were correspondingly characterized,and its luminescence characteristics and luminescence mechanism were studied.