Preparation Of One-dimensional Lanthanide Oxyfluoride And Fluoride By Electrospinning

It is valuable that nanotechnology is applied in luminescence material. New luminescence material would be available and of great value in various applications if the combination of nanotechnology property and luminescence material were done. Lots of researchers have been bent on studying the outlandish property of these sorts of materials.Rare-earth (RE) has abundant electronic energy levels because of its peculiar atomic structure. It could be applied in lighting, phosphors and solid-state lasers. As the further study is carrying on year in year out, RE doped materials turn to be performing well in high-tech and optical telecommunications.RE oxyfluoride materials have been investigated for application to phosphors and ionic conductors. It incurs intensive study. Owing unique electronic and optical property, RE oxyfluoride materials have potential value in application of optical device, optoelectronic nano-device and semiconductor.Many people did the work of synthesis RE oxyfluoride. As the literature reporting, solid-state process and electrolysis are the main methods to synthesize RE oxyfluoride. However, the reaction condition is always rigorous and the cost is considerable.RE ion doped fluoride has great range of applications in optical electronic device, lasers, optical electronic device and display. Non-radiative loss of RE ions ought to be minimized when lighting. Fluoride has an advantage as a fluorescent host matrix owing to their low phonon energy. And the fluorescence would be more efficient. We combined electrospinning with RE ion doped fluoride together.Electrospinning is a simple and versatile method to fabricate one-dimensional (1D) material. With the constant advances in technology, electrospinning is able to fabricate not only organic material, but also organic/inorganic composition and inorganic material. Functional composite nanofibers achieved by these methods have been widely used in the applications of electronic and optical nano-devices, chemical and biological sensors, catalysis and electrocatalysis, superhydrophobic surfaces, environment, energy, and biomedical fields.It is for only several years that electrospinning has been applied to fabricate RE ion doped material, and there are few reports. It has been done that the RE ion doped composition and inorganic 1D materials have been synthesized. Nevertheless, oxygen is one of components of these inorganic materials. The synthesis of 1D lanthanide fluoride has not been reported yet.In our study, we have fabricated 1D YOF and YF₃ micro- and nano-fibers. The main results are as follows:(1) We mixed the PVP ethanol and Y(CF₃COO)₃ solution. After server stirring, the precursor of electrospinning was obtained. Then the PVP/ Y(CF₃COO)₃ composition fibers were spun. The diameter of fibers changed by shifting the parameters of electrospinning. The pure PVP fibers are fine columns. If the Y(CF₃COO)₃ were added, the section of the composition fiber would be elliptical.(2) The PVP/ Y(CF₃COO)₃ composition fibers turn to be YOF fibers after the heat treatment. The XRD pattern showed that the sample was YOF. The products were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The TEM image showed that the lots of particals of which mean diameter was about 45 nm made up an entire fiber. PVP was carbonized and Y(CF₃COO)₃ yielded YF₃ at 300℃. The YF₃ crystallized in the PVP mold. When the temperature rose to 600℃, all of the PVP was burned out and the YF₃ turned to YOF. In the crystallization process, the YOF crystal would have formed continuous fiber if the proportion of PVP to Y(CF₃COO)₃ was reasonable. The calcination route influenced the size of the YOF crystals. If the temperature jumped to 600℃quickly, the size would be bigger than those whose temperature rose for a long time.(3) The YOF fibers were calcined for the second time. The products proved to be YF₃ by XRD. In the calcination process, the YOF was fluoridized. The NH₄HF₂ acted as fluoridizer. The NH₄HF₂ yielded NH₃ and HF when it was heated. The fluoridization process was difficult to carry on when the diameter of YOF fiber was hundreds of nanometers. The duration of calcination influenced the crystallization. When the YOF fibers had a diameter of hundreds of nanometers, the fluoridization reaction lasted several hours. High-temperature did harm in crystallization. Three hundreds degree centigrade is the optimal calcination temperature.