Figure 6 - uploaded by Satpal Singh Sekhon
Content may be subject to copyright.
Scanning electron micrographs of conventionally processed composites, mNiO-(1-m)YSZ: (a) 20NiO-YSZ CON, (b) 30NiO-YSZ CON, (c) 40NiO-YSZ CON and (d) 50NiO-YSZ CON.
Source publication
In the present study, microwave energy (2·45 GHz) has been used to prepare nickel oxide-yttria stabilized zirconia (NiO-YSZ)
composites of composition, mNiO-(1 − m) Zr0·9Y0·1O1·95 (m = 0·2, 0·3, 0·4, 0·5 and 0·6), from a precursor obtained by mixing NiO, Y2O3 and monoclinic ZrO2 in their stoichiometric ratio. The composites have been prepared by co...
Contexts in source publication
Context 1
... scanning electron micrographs of conventionally sintered composites, mNiO-YSZ CON for m = 0⋅2, 0⋅3, 0⋅4 and 0⋅5, are shown in figure 6(a-d). The SEM of conventionally sintered composites, mNiO-YSZ CON, as shown in figure 6 reveals that the agglomeration of NiO is more even in the 0⋅2NiO-YSZ CON composite unlike in microwave sintered 0⋅2NiO-YSZ MW composite in which the distribution of NiO and YSZ is uniform. ...
Context 2
... scanning electron micrographs of conventionally sintered composites, mNiO-YSZ CON for m = 0⋅2, 0⋅3, 0⋅4 and 0⋅5, are shown in figure 6(a-d). The SEM of conventionally sintered composites, mNiO-YSZ CON, as shown in figure 6 reveals that the agglomeration of NiO is more even in the 0⋅2NiO-YSZ CON composite unlike in microwave sintered 0⋅2NiO-YSZ MW composite in which the distribution of NiO and YSZ is uniform. Also, the grain growth of YSZ in this conventionally sintered com- posite is low as compared to that of 0⋅2NiO-YSZ MW microwave sintered composite. ...
Similar publications
A new Ti5Te4-type compound, Zr stabilized hafnium telluride was discovered and characterized with electron crystallography. Microanalyses and preparative work show that Zr stabilizes Ti5Te4- type hafnium telluride and destabilizes the competing phase, Hf3Te2
Citations
... A few interesting reports have appeared on microwave solid-state synthesis of complex oxides e.g. BaTiO 3 [49], CSZ [50], YSZ [51][52][53][54], CGO [55], and YZT [56]. ...
The paper reported calcination and sintering of apatites of compositions La9.5Ge5.5Nb0.5O26.5 and La9.5Ge5.5Mn0.5O26 using microwave energy for the first time from the precursor prepared by the mixed oxide method. The calcination was done conventionally under an identical condition to compare the results. The single phase of La9.5Ge5.5Nb0.5O26.5 and La9.5Ge5.5Mn0.5O26 could be obtained by microwave processing at temperature 1100 °C within 1 h. But the single phase of aptites could not be prepared by conventional heating under the identical conditions. The calcined powder obtained by microwave heating was sintered by microwave heating as well as conventional heating. The products obtained were characterized by XRD and SEM. It was observed that the microwave sintered products had higher density and uniform microstructure compared to the sintered products obtained by the conventional heating.
... From the refinement, it is inferred that YSZ and NiO are in cubic phase (space group: Fm3m). The cubic phase of YSZ and NiO has been indentified from (111) and (200) peaks respectively [16]. The lattice parameters observed for YSZ is 5.139 Å, while that for NiO is 4.176 Å. ...
... Few agglomerations of small size grains are also seen. In case NiO/YSZ composites, the surface morphology significantly depends upon the concentration of NiO and YSZ [16]. The dissolution limit of NiO in YSZ is the key factor in determining the lattice parameter as well as grain growth habit of the composition. ...
... The dissolution limit of NiO in YSZ is the key factor in determining the lattice parameter as well as grain growth habit of the composition. The dissolution of NiO in YSZ is significantly depends upon the ionic radius and it may be noted that the ionic radius of Ni 2+ is small in comparison to both the Zr 4+ and Y 3+ [16]. The mismatch between ionic radius leads to such non-uniform grain morphology. ...
The current article presents first-hand work on the synthesis of nickel oxide–titania-doped yttria-stabilized zirconia (NiO-YZT) composites of composition 0.40NiO-0.60{[(ZrO2)0.92(Y2O3)0.08]1−x(TiO2)x} with x = 0.00, 0.03, 0.06, 0.09, 0.12 and 0.15 using microwave processing. The composites are prepared by mixed oxide method by taking yttria (Y2O3), titania (TiO2) and monoclinic zirconia (ZrO2) in their stoichiometric ratio and sintered by using conventional and microwave processing techniques. The investigation of prepared composites has been carried out by x-ray diffractometer, scanning electron microscope and Vickers hardness technique to probe the crystal structure, microstructure and mechanical properties. Also, the results obtained are compared for both the conventionally and microwave-sintering routes. It was inferred that the microwave-sintered NiO-YZT showed better results than the conventional samples in terms of greater density, uniform microstructure and better microhardness.
Zirconia-based ceramic oxides Zr0.90Y0.06Ce0.02X0.02O2−δ (X = Ca, Fe, La, Sr, and Mg) were prepared by conventional and microwave processing. The precursors of Zr0.90Y0.06Ce0.02X0.02O2−δ (X = Ca, Fe, La, Sr, and Mg) were prepared by a mixed oxide method and were calcined at 600°C in an electric furnace. The powders were consolidated in pellet form and sintered in a conventional electric furnace at 1400°C for 6 h and compared using microwave energy at 1400°C for 20 min. The structure and microstructure of sintered products obtained by both methods were studied by x-ray diffraction and scanning electron microscopy. Their density and microhardness were also compared. The electrical conductivities of these samples were studied using alternating current impedance spectroscopy. The analysis of the products obtained by microwave aand conventional methods shows that the microwave sintered samples have uniform grain growth, higher density, higher microhardness and higher electrical conductivity than the corresponding conventionally sintered products. The microwave sintered sample of composition Zr0.90Y0.06Ce0.02Ca0.02O2−δ was found to have the highest density and microhardness, as well as the highest electrical conductivity among all of the microwave and conventionally sintered products.
A simple and cost effective combustion process is employed to prepare Ni/YSZ cermet from an aqueous solution containing ZrO(NO3)2·6H2O, Y(NO3)3·6H2O, Ni(NO3)2·6H2O and urea followed by H2 reduction. As prepared cermet was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy techniques. Processed powder of NiO-YSZ was found to be in crystalline form with homogeneous mixture of YSZ and NiO phases. On reduction, its mixed conductivity is suppressed partially. The impedance and dielectric properties of the cermet were studied over a frequency range 10 Hz to 2 MHz at different temperatures. M ̴ H behavior at different temperature (down to 5 K) including ZFC and FC at 500 Oe were studied. To understand and corroborate the conductivity behavior and mechanism involved with the magnetic Ni ion mediated YSZ cermet, we have also studied the electric field induced polarization behavior and predict that Ni magnetic ion has specific role towards the contribution of conductivity mechanism generally included in Ni/YSZ cermet used for SOFC applications.
Doped and co-doped ceria ceramics are used as electrolyte materials in solid oxide fuel cells. In this work, ceria-based oxides, Ce0.90Gd0.06Y0.02M0.02O2−δ (M = Ca, Fe, La, and Sr) were prepared by conventional as well as microwave processing from the precursors prepared by the mixed oxide method. The consolidated calcined powders in pellet form were sintered in microwave energy at 1400°C for 20 min and in an electric furnace of IR radiation at 1400°C for 6 h. The x-ray diffraction analysis confirmed that all the compositions were crystallized into a cubic fluorite structure. Surface morphology of the sintered products was studied using scanning electron microscopy and the microhardness was investigated using the Vickers hardness test. The comparative results analysis shows that the microwave-sintered samples have uniform grain growth, higher density and higher microhardness than the corresponding conventionally sintered products. The microwave-sintered sample of composition Ce0.90Gd0.06Y0.02Sr0.02O2−δ was found to have the highest microhardness among the four compositions due to its high density and smallest grain size.
An effective and facile technique has been developed for high temperature anode-electrolyte co-sintering of anode support solid oxide fuel cells by using microwave activated sparking plasma. A high sintering temperature of 1600 degrees C can be achieved in a few minutes time by discharging effect. Anode support substrate pellet is uniaxially pressed, and then dip-coated with a 10 mu m yttria stabilized zirconia electrolyte layer. After the microwave co-sintering, La(0.8)Sr(0.2)MnO(x),, cathode is screen-printed onto electrolyte and sintered by conventional thermal method. The cell has stably operated in 3% humidified hydrogen for more than 130h. (C) 2011 Elsevier B.V. All rights reserved.
