For the selective catalytic reduction of NOx with ammonia (NH3-SCR), a V2O5WO3/TiO2 (VW/nTi) catalyst was prepared using V2O5 and WO3 on a nanodispersed TiO2 (nTi) support by simple impregnation process. The nTi support was dispersed for 0~3 hrs under controlled bead-milling in ethanol. The average particle size (D50) of nTi was reduced from 582 nm to 93 nm depending on the milling time. The NOx activity of these catalysts with maximum temperature shift was influenced by the dispersion of the TiO2. For the V0.5W2/nTi-0h catalyst, prepared with 582 nm nTi-0h before milling, the decomposition temperature with over 94 % NOx conversion had a narrow temperature window, within the range of 365-391 °C. Similarly, the V0.5W2/nTi-2h catalyst, prepared with 107 nm nTi-2h bead-milled for 2hrs, showed a broad temperature window in the range of 358~450 °C. However, the V0.5W2/Ti catalyst (D50 = 2.4 μm, aqueous, without milling) was observed at 325-385 °C. Our results could pave the way for the production of effective NOx decomposition catalysts with a higher temperature range. This approach is also better at facilitating the dispersion on the support material. NH3-TPD, H2-TPR, FT-IR, and XPS were used to investigate the role of nTi in the DeNOx catalyst.

The grain growth behavior in the (1-x)K0.5Na0.5NbO3-xCaZrO3 (KNNCZ-x) system is studied as a function of the amount of CZ and grain shape. The (1-x)K0.5Na0.5NbO3-xCaZrO3 (KNNCZ-x) powders are synthesized using a conventional solid-state reaction method. A single orthorhombic phase is observed at x = 0 – 0.03. However, rhombohedral and orthorhombic phases are observed at x = 0.05. The grain growth behavior changes from abnormal grain growth to the suppression of grain growth as the amount of CaZrO3 (CZ) increases. With increasing CZ content, grains become more faceted, and the step-free energy increases. Therefore, the critical growth driving force increases. The grain size distribution broadens with increasing sintering time in KNNCZ-0.05. As a result, some large grains with a driving force larger than the critical driving force for growth exhibit abnormal grain growth behavior during sintering. Therefore, CZ changes the grain growth behavior and microstructure of KNN. Grain growth at the faceted interface of the KNNCZ system occurs via two-dimensional nucleation and growth.

In this study, the effects of kaolin addition on the properties of reticulated porous diatomite-kaolin composites are investigated. A reticulated porous diatomite-kaolin composite is prepared using the replica template method. The microstructure and pore characteristics of the reticulated porous diatomite-kaolin composites are analyzed by controlling the PPI value (45, 60, and 80 PPI) of the polyurethane foam (which are used as the polymer template), the ball-milling time (8 and 24 h), and the amount of kaolin (0–50 wt. %). The average pore size decreases as the amount of kaolin increases in the reticulated porous diatomite-kaolin composite. As the amount of kaolin increases, it can be determined that the amount of inter-connected pore channels is reduced because the plate-shaped kaolin particles connect the gaps between irregular diatomite particles. Consequently, a higher kaolin percentage affects the overall mechanical properties by improving the pore channel connectivity. The effect of kaolin addition on the basic properties of the reticulated porous diatomite-kaolin composite is further discussed with characterization data such as pore size distribution, scanning electron microscopy images, and compressive strength.

The grain growth behavior of M-type Sr hexaferrite (SrM) grains is investigated with the addition of MnCO3. First, the SrM powder is synthesized by a conventional solid-state reaction. The powder compacts of SrM are sintered at 1250oC for 2 h with various amounts of MnCO3 (0, 0.5, 1.0, and 4.0 mol%). There is no secondary solid phase in any of the sintered samples. Relative density increases when MnCO3 is added to the SrM. Obvious abnormal grain growth does not appear in any of the SrM samples with MnCO3. The average grain size increases when 0.5 mol% MnCO3 is added to the SrM. However, as the amount of MnCO3 increase to over 0.5 mol%, the average grain size decreases. These observations allow us to conclude that the growth of SrM grains is governed by the two-dimensional nucleation grain growth mechanism, and the critical driving force for the growth of a grain decreases as the amount of MnCO3 increases.

Fe3O4/SiO2/YVO4:Eu3+ multifunctional nanoparticles are successfully synthesized by facile stepwise sol-gel processes. The multifunctional nanoparticles show a spherical shape with narrow size distribution (approximately 40 nm) and the phosphor shells are well crystallized. The Eu3+ shows strong photoluminescence (red emission at 619 nm, absorbance at 290 nm) due to an effective energy transfer from the vanadate group to Eu. Core-shell structured multifunctional nanoparticles have superparamagnetic properties at 300 K. Furthermore, the core-shell nanoparticles have a quick response time for the external magnetic field. These results suggest that the photoluminescence and magnetic properties could be easily tuned by either varying the number of coating processes or changing the phosphor elements. The nanoparticles may have potential applications for appropriate fields such as laser systems, optical amplifiers, security systems, and drug delivery materials.

Grain-growth behavior in the 95Na1/2Bi1/2TiO3-5BaTiO3 (mole fraction, NBT-5BT) system has been investigated with the addition of Na2CO3. When Na2CO3 is added to NBT-5BT, the growth rate is higher than desired and grains are already impinging each other during the initial stage of sintering. The grain size decreases as the sintering temperature increases. With the addition of Na2CO3, a liquid phase infiltrates the interfaces between grains during sintering. The interface structure can be changed to be more faceted and the interface migration rate can increase due to fast material transport through the liquid phase. As the sintering temperature increases, the impingement of abnormal grains increases because the number of abnormal grains increases. Therefore, the average grain size of abnormal grains can be decreased as the temperature increases. The phenomenon can provide evidence that grain coarsening in NBT-5BT with addition of Na2CO3 is governed by the growth of facet planes, which would occur via mixed control.

The grain growth behavior of (NBT-5BT) has been investigated with respect to the grain shape. The powder compacts of NBT-5BT were sintered at 1200 for various times. The corresponding equilibrium shape was a round-edged cube with flat {100}-faces. Abnormal grains were not observed in the specimens sintered for 1 to 12 h but abnormal grains appeared when sintered for 24 h. Before the formation of abnormal grains, a valley was observed in the measured grain size distribution of NBT-5BT, showing that the grain size distribution was a combination of two unimodal distributions. The present result suggests that the grain growth in NBT-5BT was governed by the growth of facet planes which would occur via 2-dimansional nucleation and growth