Preparation And Characterization Of Rare Earth Composite Oxides Upconversion Nanofibers By Electrospinning Method

In recent years, investigation on nanofibers has aroused much attention of the scientists all over the world due to their unique characteristics such as very large surface area to volume ratio, flexibility in surface functionalities, and superior mechanical performance compared with any other known form of the materials. There has been an intense interest recently in the investigation of upconverting phosphor compounds that produce emitted photons with a higher energy than the excitation photon energy. These outstanding properties make the upconversion luminescence be the optimal candidates for many important applications, such as all-solid compact laser devices, infrared quantum counter detectors and fluorescent labels for sensitive detection of biomolecules. Preparation, properties and applications of these compounds have become an important research field.In the dissertation, PVA/inorganic salts composite nanofibers were fabricated by sol-gel process and electrospinning technique, using polyvinylalcohol (PVA Mn=80000) and various inorganic salts as starting materials. Y₂O₃, Y₂O₃:Er³⁺, Y₂O₂:Yb³⁺:Er³⁺, Gd₂O₃:Yb³⁺:Er³⁺ nanofibers were obtained by calcinations of the relative composite nanofibers. This method offered a brand-new way for fabricating one-dimensional inorganic upconversion nanomaterials.The PVA/inorganic salts composite nanofibers and rare earth oxides nanofibers were characterized by scanning electron microscope(SEM), Fourier transform infrared spectrometer(FTIR). X-ray diffraction(XRD) and thermal analysis(TGA-DTA). All the results show that the favorite nanofibers with smooth surface, homogeneous diameters of 50-100nm and uniform morphology were obtained. At room temperature, these three kinds of upconversion luminescence nanofibers namely Y₂O₃:Er³⁺, Y₂O₃:Yb³⁺:Er³⁺, Gd₂O₃:Yb³⁺:Er³⁺ were excited by 980nm laser and the upconversion luminescence were achieved. The upconversion emission spectra of the upconversion luminescence nanofibers were similar to these of the relative upconversion luminescence particles.