Papers by Keyword: CeO₂

Abstract: Cerium oxide (CeO₂) or known as ceria were deposited on titanium dioxide, TiO₂, nanotubes by electrodeposition process as to produce hybrid materials that can generate photocurrent. The electrodeposition process is done by using 0.1 M cerium chloride mixed with 0.1 M ammonium acetate as ligands to promote stability complexes in a standard two electrode bath. Voltage and pH were controlled to ensure the most optimum condition of cerium oxide deposition. Samples were then annealed at different temperatures. Photocurrent results indicate that annealed sample at 450°C shows the best photocurrent due to high degree of anatase and cubic crystallinity.

Abstract: Porous CeO₂ nanostructures were synthesized by a simple template method using cotton fibers as biomaterial template. The phase structure and morphology of the product were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM). The UV-blocking property was evaluated by UV-Vis spectrophotometry. Experimental results showed that the as-synthesized CeO₂ was in a cubic fluorite structure and presented fiber-like structure. The fiber-like CeO₂ nanostructures completely recorded the original morphology of cotton fibers, which consisted of large amounts of coalescent CeO₂ nanoparticles with average particle size in the range of 6-10 nm. The UV test result showed that the UV transmittance of the product was closer to zero in the wavelength below 350 nm, indicating that the product exhibited excellent UV-blocking property.

Abstract: Catalysis combustion-supporting agent of coal powder is the important measure to improve the combustion process of coal powder, so the study on catalysis combustion-supporting agent draws the attention of many scholars. The paper studies the influence of CeO₂ and MnO₂ addition on ignition temperature, burnout temperature, explosiveness and calorific value of coal powder, and analyzes the catalytic mechanism of CeO₂ and MnO₂ catalysis combustion-supporting agent.

Abstract: To improve bioactivity of gradient bioceramic coating, the coating with two kinds of rare earth oxide was produced by wide band laser cladding technique. As the experimental results, whichadded0.6wt.% La₂O₃ fixedly, and increased the addition amount of the CeO₂, when the addition of CeO₂fulfill 0.4wt.%, the amount of HA-β-TCP is the largest in this experiment. Soaking the specimens in SBF for 14 days, the coating blended 0.6wt% La₂O₃ and 0.4wt% CeO₂, then a great quantity of Ca-P white particles can be found on coating, which confirmation this bioceramic coating is of best bioactivity.

Abstract: We report a facile hydrothermal synthesis in base solution for shape/size-controlled ceria (CeO₂) nanocrystals and CeO₂-ZrO₂ solid solution. CeO₂ nanocrystals in the shape of nanorods, nanotubes, or nanocubes with reactive {110} and {200} faces can be produced using this hydrothermal method. We found that hydrothermal reaction temperature is a critical parameter to control the shape and size of ceria nanocrystals. Above 210 °C, high resolution transmission electron microscopy studies revealed that the CeO₂ nanocubes expose predominant {200} crystal planes. Microscopic investigation showed that the CeO₂-ZrO₂ solid solutions synthesized using this method had high crystallinity, and compositional homogeneity, and improved low-temperature reducibility.

Abstract: Cubic Yttria-stabilized zirconia (c-YSZ) is a candidate material for high temperature applications due to its chemical inertness, high thermal stability and low thermal conductivity. In addition, due to c-YSZ’s high radiation stability, there is a new interest in this ceramic for thermal insulating cladding material in Supercrticial Water Nuclear Reactors (SCWR). However, due to the aggressive environment of supercritical water, the degradation behaviour of the ceramic must be well understood prior to its industrial application. In this research, moderately dense 8 mol% Yttria stabilized zirconia (YSZ) as well as YSZ composites containing 5, 10 and 15 mol% CeO₂ were fabricated via Spark Plasma Sintering (SPS) and subjected to static corrosion testing in supercritical water (SCW) at 400°C and 31MPa. Weight loss and crystal lattice changes associated with SCW exposure were studied.

Abstract: In o rder to research the influence of anion additives/ CeO₂ on cabbage seeds, taking cabbage seeds as the test material. This paper detected the seeds' germination percentage and protein content by respectively adding unique concentration of anion additives and CeO₂ in soil. The results show that different anion additives have distinct influences on seed's growth in the same situation. To be more specific, 1040 can noticeably improve seeds' germination percentage and protein content. Moreover, different contents of 1040 could have various impacts on seeds' germination percentage and protein content. Furthermore, precise content of CeO₂ can also significantly improve seeds' germination rate and protein accumulation.

Abstract: The properties of CeO₂ -LaB₆/B₄C composite material prepared by hot pressed sintering method was tested, CeO₂ as a sintering aid for boron carbide is investigated in this paper. The study shows: the hardness of CeO₂ -LaB₆/B₄C composite increases with the content of CeO₂. The density, hardness, flexibility strength and the fracture toughness of LaB₆/B₄C composites is greatly improved compared by CeO₂ additive. When the content of the CeO₂ is 1wt%, LaB₆/B₄C composite has its the best mechanical properties. The density reaches its supreme value of 2.676 g/cm³, the hardness reaches its supreme value of 39.19 GPa, the flexibility strength reaches its supreme value of 354.15 MPa and the fracture toughness reaches its supreme value of 5.15 MPa.m^1/2. In conclusion, the density, hardness and flexibility strength of LaB₆/B₄C composite is improved by CeO₂ additive. However,it gives little effect on fracture toughness of LaB₆/B₄C composite. The main fracture way of CeO₂-LaB₆/B₄C composite material is intercrystalline rupture, while the transcrystalline rupture is minor.

Abstract: The CeO₂ is prepared directly from bastnaesite as raw material that originated in Dechang, Sichuan province, China. Fully mixed with sodium bicarbonate (NaHCO₃) and roasted at 550 °C, the rare earth element (REE) in bastnaesite transformed into rare earth oxide. And the CeO₂ will be obtained by removing NaF through water washing and leaching the impurity elements including La, Fe, Al, Ca, etc. via hydrochloric acid (HCl). The CeO₂ was characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF). The XRF results demonstrated that the content of CeO₂ could reach more than 70% in products which can be used as polishing material.

Abstract: NOx is the main air pollutant of coal-fired power plants, which is one of the important reasons to cause pollution such as acid rain, photochemical smog and so on. Selective catalytic reduction process is the major technology for reducing NOx emissions from coal-fired power plants. However, the commercial vanaidia-based catalyst is active within a narrow temperature window of 300-400°C, easily to be deacticed by SO₂ in the flue gas. And the formation of N₂O and toxicity of vanaidia cause secondary pollution. Therefore, it is of more importance to develop a new environmental-friendly catalyst for low temperature SCR with high activity.