Papers by Keyword: La Doping

Abstract: The conventional TZM alloy plates have limited manufacture and application due to the lacking of enough mechanical property. To resolve this question, La doped TZM alloy plate was made by the powder metallurgy. With solid-solid rare La₂O₃ doping, sintering, hot rolling, warm rolling and cold rolling, the molybdenum alloy La-TZM plates were got. This kind of TZM alloy has better properties in both strength and elongation. The tensile strength of La-TZM alloy is 1038 MPa, and the elongation is 10.4%. Metallography test and scanning electron microscopy (SEM) are used to examine the microstructure of the La-TZM alloy plate specimen.

Abstract: Influences of different amount of La-substituted on structural and magnetic properties of M-type strontium ferrites SrLa_xFe_(12−x)O₁₉ compounds prepared by an aqueous solution method have been systematically investigated by XRD, VSM and TEM. In this work, it is found that only magnetoplumbite structure exists in the sample rather minorphases from the XRD patterns. When the doping content is x≤0.06mol, substituting of La³⁺ for Fe³⁺ occurs, forming SrLa_xFe_(12-x)O₁₉. In contrast, when the doping content is x>0.06mol, Sr2+ is substituted by La³⁺, forming Sr_(1-x)La_xFe₁₂O₁₉. The saturation magnetization (σs) shows its maximum at x=0.04 while the peak value of the intrinsic coercive field (Hjc) presented at x=0.06 as the La substituted content increases. The obtained results also indicated that the shape of the formed SrLa_xFe_(12−x)O₁₉ is oblong with 70nm length and 40nm width.

Abstract: Lanthanum doping TiO2 powders were prepared using sol-gel method, and characterized by XRD. The doping quantity, time of solar irradiation and the added quantity of catalyst were investigated for the influence on the photocatalytic degradation of bisphenol A. The results show the structure of La3+ doped TiO2 powders were anatase, particle size were 16 nm. For the initial concentration of bisphenol A solution were 50 mg/L , when the doping quantity of La were 1.0 wt %, the dosing quantity of TiO2 were3.6 g/L, PH value were acid, irradiation time were 2 h, the photocatalytic activity of TiO2 was the best.

Abstract: In this present work, rare earth elements La was added to catalysts for the oxidative esterification of methacrolein (MAL) to methyl methacrylate(MMA). Catalysts were characterized by means of BET techniques. Effects of La proportion, material liquid pH and catalyst amount on catalytic performance were investigated. The results indicated that the addation of La in appropriate proportion could improve the catalyst’s activity. 1.0% was found to be the optimum La additional amount. Under the condition of reation temperature 323K, w%(catalyst) 3.6%, proportion of La in the catalyst 1%, pH of material liquid 10.0 the MMA yield could reached up to 89.8%.

Abstract: Ni ferrites doped with lanthanum with a nominal composition of NiFe2-xLaxO4(x=0.05) were obtained by mechanochemical treatments using NiCO3•2Ni (OH)2•4H2O , La2O3 and Fe2O3 as raw materials. Both series of materials were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM). The results indicated that the mixture became amorphous stage after ball-milled for 30 h, and single phase NiFe1.95La0.05O4 could be obtained after calcined at 700 for 2 h. The addition of lanthanum resulted in a reduction of all the magnetic parameters evaluated.

Abstract: Bi4-xLaxTi3O12 (BLT, x=0, 0.75, 1, 2) ceramic powders were prepared with sol-gel and solid phase reaction processes, respectively. BLT powders were synthesized after decarbonization at 300°C for 1h followed by calcination at 800°C for 2h. The ceramics synthesized with cold isostatic pressing and sintering at 1150°C exhibit a perovskite-like structure. The influence of sintering parameters and La doping content on density, microstructure and dielectric properties of the BLT were discussed. With the increase of La doping content in Bi4-xLaxTi3O12, dielectric constant increases and dielectric loss gradually decreases. The dielectric constant and dielectric loss of Bi4-xLaxTi3O12 (x=2) are 132.7 and 0.012 at 100 KHz, respectively.