Electrochemical Synthesis And Characterization Of Rare-earth Nanomaterials

Rare-earth compounds have been widely used in high performance luminescent devices, catalysts, magnets, and other functional materials owing to the numerous well-defined transition modes involving the 4f shell of their ions. According to these extensive usage, the rare-earth nanomaterials have attracted grate research interest in recent years.As a facile, low process temperature, low cost and capability of controlling grain size, morphology synthesis method, electrodeposition method has been widely used in preparing materials; it also has showed strong potential in producing nanomaterials. The electrochemical synthesis, characterization, mechanism of the process and optical properties of CeF₃, LaF₃ and its rare-earth doped compounds, and CePO₄ nanomaterials are well discussed in this paper.To begin with, the Ce³⁺-EDTA and NH₄F contained solution is used as the reactor to produce CeF₃ deposits. In the electrodeposition progress, the local pH value at the work electrode surface is decreased by electrochemically oxidizing water and the stability of Ce³⁺-EDTA complex is decreased to release free cerium ions into solution to form CeF₃ deposits. The CeF₃ samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectra and photoluminescence spectra (PL). The experimental results show that as-prepared CeF₃ film has uniform microspheres. In a higher resolution SEM image, it can be seen that the film is actually composed of many spherical-shaped particles. Meanwhile, the effect of the deposition temperatures and deposition potentials on the morphologies of the CeF₃ thin films has been investigated, and the mechanism of electrodeposition progress has also been discussed.Secondly, we have produced LaF₃ and rare-earth doped in it materials by facile electrodeposition method. The La³⁺-EDTA and NH₄F contained solution is used as the reactor together with ascorbic acid. In the electrodeposition progress, the local pH value at the work electrode surface is decreased by electrochemically oxidizing ascorbate and the stability of La³⁺-EDTA complex is decreased to release free lanthanum ions into solution to form LaF₃ deposits. The LaF₃ samples were characterized by XRD, SEM, and UV-vis spectra. The optical properties of LaF₃:Ce, LaF₃:Tb, LaF₃:Eu and LaF₃:Tb:Eu have been well researched by photoluminescence spectra (PL). The experimental results show that as-prepared LaF₃ film has uniform microspheres. Meanwhile, the effect of the deposition potentials on the morphologies of the LaF₃ thin films has been investigated.Finally, the Ce³⁺-EDTA and Na₃PO₄ contained solution is used as the reactor to produce CePO₄ deposits. In the reaction process, the pH value of the solution system is decreased by electrochemically oxidizing water and the stability of Ce³⁺-EDTA complex is decreased to release free cerium ions into solution to form CePO₄ deposits. The experimental results show that the deposition potentials have great influence on the as-prepared CePO₄ samples.