Effect of Ions Substitution on Nanospace La-Fe-O Catalytic Properties for Simultaneous Removal of NOx and Soot

The catalysts La0.8K0.2FeO3(LKFO), La0.8K0.2Fe0.7Mn0.3O3(LKFMO) and La0.8K0.2Fe0.67Mn0.3Pt0.03O3(LKFMPO) were prepared by the citrate-gel process and the catalyst-coated honeycomb ceramic devices were prepared by the citrate-gel assisted dip-coating method. All the catalysts have a high performance on the simultaneous removal of NOxand soot at a temperature range of 200 to 400°C under the practical diesel exhaust emission. The obvious catalytic improvement is largely due to the effects of ions substitution, pore structure and microstructural characteristics of the catalysts. The catalytic performance order is LKFMPO > LKFMO > LKFO. Among them the LKFMPO catalyst shows the best catalytic properties, especially in the removal of NOx, with a maximum conversion rate of NOx(21.2%).

Synthesis and Characterization of Magnetoelectric Nanocomposites

A simple citrate gel process was used to prepare nanocomposites of xCuFe2O4–(1−x)BiFeO3 (henceforth, CFBF) and xNi0.75Co0.25Fe2O4-(1-x)BiFeO3 (henceforth, NCFBF) with x=0.1, 0.2, 0.3 and 0.4. The phase was found to be formed at 500 °C and 700 °C for CFBF and NCFBF respectively. TEM observation showed that the average particles size is around 40 nm. The variation of the dielectric constant and the dielectric loss with frequency showed dispersion in the low frequency range. All the samples exhibit strong magnetic characteristics. The coercivity and squareness increased with the increase in annealing temperature and were maximum for samples annealed at 500°C and 700°C for CFBF and NCFBF nanocomposites, respectively, and further decrease in coercivity is attributed to decrease in aspect ratio and pinning effects in the nanocrysatllites. The ME coefficient αE showed strong dependence on HBias and maximum value of ME coefficients were 303 and 309 mV/cm Oe at magnetic field frequency of 50 kHz for CFBF and NCFBF nanocomposites respectively. The large values of ME coefficients are attributed to low coercivity, large magnetization and small crystallite size of constituent phases.

Low Temperature Synthesis and Characterization of CaO and MgO- Stabilized Nanocrystalline Tetragonal Zirconia by Citrate Gel Process

The citrate gel method, similar to the polymerized complex method, was used to synthesize homogenous tetragonal zirconia at 800oC and 1000oC. Nanocrystalline tetragonal single phase has been fully stabilized with 3, 7, 10 mol% CaO and 10, 15 mol% MgO at 800oC, respectively. In addition, the XRD analysis showed the absence of monoclinic phase after addition of 7 and 10 mol% CaO into zirconia-based solid solutions, which have been fully stabilized both 800oC and 1000oC. The crystallite sizes of the t-ZrO2 with 3, 7 and 10 mol% CaO at 1000oC were 32, 28 and 29nm, respectively. For ZrO2- x mol% MgO (x=3, 10, 15) solid solution, the crystallite sizes of samples at 800oC were less than 29nm, however it was increased up to 69nm at 1000oC. The prepared gel and subsequent heat-treated powders were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) to get detail information regarding to differentiation of polymorphs of zirconia as well as formation of powders.