Papers by Keyword: Glycine-Nitrate Process

Abstract: Utilizing two different synthesis methods, solid-state reaction and glycine-nitrate process, composite lanthanum strontium manganite and yttria-stabilized zirconia (LSM-YSZ) powders were prepared. The powders were then mixed with 0, 5, and 10 wt% carbon black nanosized pore former and pressed into 10mm diameter pellets then sintered at 1150 °C for 5 hours. The pellet composition and microstructure were investigated using FTIR, XRD, SEM-EDX, and their density and open porosity were measured using the Archimedes principle. The resulting microstructure of the composite pellets obtained using the two fabrication methods and different pore former weight percentages were studied and compared. It was found that the addition of 5 wt% carbon black pore former yields about 40% desired open porosity, and synthesis via GNP results to finer and more evenly distributed LSM and YSZ particles.

Abstract: In this study, the effects of glycine-nitrate ratios and postcombustion chemical treatment on the phase evolution and surface area of CuCrO₂ powders were investigated. The pure phase of CuCrO₂ powders was obtained at a glycine-nitrate ratio of 1.2–1.4. When the glycine-nitrate ratio was higher than 1.9, the Cu ions were reduced to Cu(0) and the phase of Cu metal and Cr₂O₃ were observed. However, when the glycine-nitrate ratio was lower than 1.1, the Cu ions were partially maintained as Cu(2⁺), and a bluish residue was observed. As-combusted CuCrO₂ powder with a high surface area (50 m²/g) was obtained at a glycine-nitrate ratio of 1.2. Furthermore, a high surface area (> 60 m²/g) was obtained by leaching as-combusted CuCrO₂ powder with diluted nitric acid.

Abstract: Pr_1.2Sr_0.8NiO₄ (PSNO) and Sm_0.2Ce_0.8O_1.9 (SCO) powders were synthesized by a glycine-nitrate process and a gel-casting process, respectively. Pr_1.2Sr_0.8NiO₄-x Sm_0.2Ce_0.8O_1.9 (x=0, 25, 50) composite cathode materials were prepared by mechanically mixing the two powders. The particle size of the synthesized PSNO and SCO powders is about 100nm and 50nm, respectively. PSNO and SCO have a good chemical compatibility. Area specific resistance value for the Pr_1.2Sr_0.8NiO₄-x Sm_0.2Ce_0.8O_1.9 (x=25, 50) composite cathode on SCO electrolyte is 0.087 and 0.076Ωcm² at 750°C, which indicates Pr_1.2Sr_0.8NiO₄-Sm_0.2Ce_0.8O_1.9 composite materials may be a promising cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC).

Abstract: Manganese-Zinc ferrites belong to the group of soft ferrite materials characterized by high magnetic permeability and low power loses. These materials are mainly used as cores for inductors, transformers, recording heads and noise filters among others. In this study, nanocrystalline Mn-Zn ferrite with the chemical formula Mn_1-xZn_xFe₂O₄ with x=0.2, 0.4, 0.6, 0.8 has been successfully synthesized by glycine-nitrate auto-combustion process using glycine as a fuel and nitrates as oxidants. The structures and magnetic properties of the resulting powder were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). It is revealed from the XRD pattern than a significant amount nanocrystalline Mn_1-xZn_xFe₂O₄ ferrite with average crystallite size in the range 43.25-66.7 nm has been formed. The magnetic measurement gives a typical value of saturation magnetic of 34-69 emu/g and coercivity of 40-60 Oe.

Abstract: La0.7Sr0.15Ca0.15Co1-yFeyO3-δ(LSCCF)powders with 0.2y0.5 for the applications as the cathode materials in intermediate temperature solid oxide fuel cell(ITSOFC) were synthesized by glycine-nitrates-process(GNP) using metal-nitrates and glycine as the raw materials. The process, crystal structure and particles morphology of the powders calcined at 600°C,800°C,1000°C for 3h were characterized by IR,XRD and SEM. The experimental results show that co-doped Ca2+ and Sr2+ replacing some La3+ in A site and Fe3+ replacing some Co3+ in B site didn’t influence the formation of perovskite structure and the powders calcined at 800°C for 3h were high pure single perovskite state. The electrical conductivity of LSCCF samples sintered at 1200°C for 3h,was measured as a function of temperature from 100°C to 800°C by the four-probe DC method in air.As a result, the conducting mechanism of LSCCF is p-type small polaron hopping process, and the electrical conductivity are all higher than 100 S/cm. But the electrical conductivity of LSCCF samples increase with Fe3+ content decrease.

Abstract: NiO/Ce0.8Sm0.2O1.9 (NiO/SDC, 65wt.% NiO) composite powders were synthesized by a glycine-nitrate process (GNP) to fabricate Ni/SDC anode-supported solid oxide fuel cell (SOFC). The results show that the composite powders are composed of single cubic phases of NiO and SDC and have a particle size in nanometer range. NiO/SDC ceramics were prepared from the NiO/SDC powders and were converted into Ni/SDC cermets by reduction in H2, which were employed as anode materials for SOFC with SDC electrolyte. It is shown that Ni/SDC cermets from the NiO/SDC composite powders by the GNP have porous and homogeneous microstructures and show good electrical conductivity. A single SOFC based on Ni/SDC anode with about 50µm SDC electrolyte film and about 80µm La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode was constructed. Open circuit voltage (OCV) of the cell is about 0.8V and maximum power density is 361.42 and 394.78 mWcm-2 at 750 and 800°C, respectively.

Abstract: The sintering and electronic conducting properties of La0.8Ca0.2CrO3 synthesized by a glycine-nitrate process (GNP) were investigated in comparison with that synthesized by the conventional solid state reaction (SSR) method. The results demonstrate the advantage of the GNP method in producing La0.8Ca0.2CrO3 ceramic. Compared with the powder synthesized by the SSR method, that synthesized by the GNP method shows a higher sinterability due to its fine morphology. The relative densities of the ceramics made by the GNP and SSR methods attain 96.5 % and 96.0 % when sintering at 1450°C and 1550°C, respectively. In the case of similar relative densities, the ceramic made by the GNP method (sintered at 1450°C) exhibits superior electronic conducting properties to that made by the SSR method (sintered at 1550°C). This is attributed to a desired microstructure of the ceramic made by the GNP method.