Glycine-nitrate combustion synthesis of oxide ceramic powders
TL;DR: A new combustion synthesis method, the glycine-nitrate process, has been used to prepare oxide ceramic powders, including substituted chromite and manganite powders of high quality.
About: This article is published in Materials Letters.The article was published on 1990-09-01. It has received 992 citations till now. The article focuses on the topics: Calcination & Specific surface area.
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TL;DR: This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions.
Abstract: Solution combustion is an exciting phenomenon, which involves propagation of self-sustained exothermic reactions along an aqueous or sol–gel media. This process allows for the synthesis of a variety of nanoscale materials, including oxides, metals, alloys, and sulfides. This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years. Thermodynamics and kinetics of reactive solutions used in different chemical routes are considered, and the role of process parameters is discussed, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions. The basic principles for controlling the composition, structure, and nanostructure of SCS products, and routes to regulate the size and morphology of the nanoscale materials are also reviewed. Recently developed systems that lead to the formation of novel materials and unique structures (e.g., thin films and two-dimensional crystals) with unusual...
841 citations
TL;DR: A review of sol-gel preparation of high temperature superconducting oxides is presented in this paper, where different classes of gel technologies were utilized, such as hydrolysis-condensation of metal-alkoxides, gelation, and organic polymeric gel.
Abstract: This review article focuses on the sol-gel preparation of high temperature superconducting oxides wherein different classes of gel technologies were utilized. These involve: 1) the sol-gel route based upon hydrolysis-condensation of metal-alkoxides, 2) the gelation route based upon concentration of aqueous solutions involving metal-chelates, often called as “chelate gel” or “amorphous chelate” route, and 3) the organic polymeric gel route. This paper reviews the current status of these sol-gel processes, and illustrates the underlying chemistry involved in each sol-gel technology. It is demonstrated that the chemical homogeneity of the gel is often disturbed by the differences in the chemistries of the cations. Prior to gelation the starting precursor solution containing various forms of metal-complexes must be chemically modified to overcome this problem. Illustration of a variety of strategies for success in obtaining a homogeneous multicomponent gel with no precipitation is focal point of this review article.
763 citations
TL;DR: In this paper, a review of the attempts performed thus far to mitigate the issues associated with the use of ferritic stainless steels on the cathode side is presented, including conductive/protective coatings, surface treatments and modifications as well as alloy development.
519 citations
TL;DR: In this paper, the influence of transition metal oxides additives, especially zinc oxide, on the densification and electrical properties of doped barium zirconate have been examined.
Abstract: The influence of transition metal oxides additives, especially zinc oxide, on the densification and electrical properties of doped barium zirconate have been examined. With the use of zinc oxide as a sintering aid, BaZr_(0.85)V_(0.15)O_(3-δ) was readily sintered to above 93% of theoretical density at 1300 degrees C. Scanning electron microscopic investigations showed Zn accumulation in the intergranular regions. Thermogravimetric analysis of the material under flowing CO_2 showed ZnO-modified barium zirconate to exhibit excellent chemical stability. The conductivity, as measured by A.C. impedance spectroscopy under H_2O saturated nitrogen, was slightly lower than that of unmodified barium zirconate. Electromotive force measurements under fuel cell conditions revealed the total ionic transport number to be ~0.9 at 600 degrees C. The combination of electrical and chemical properties and good sinterabifity render ZnO-modified barium zirconate an excellent candidate for reduced temperature solid oxide fuel cell applications.
503 citations
TL;DR: In this paper, a comprehensive review on the advanced synthesis of materials for intermediate-temperature SOFCs and their impact on fuel cell performance is provided, and the effect of different processes on the electrochemical performance of the materials is evaluated and optimization of the synthesis processes is discussed and some emerging synthetic techniques are also briefly presented.
374 citations
References
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TL;DR: The fine particle nature of α-alumina and related oxide materials has been investigated using SEM, TEM, particle size analysis and surface area measurements in this article, where solid combustion products have been identified by their characteristic X-ray diffraction patterns.
592 citations
368 citations
TL;DR: In this paper, the surface area and residual carbon content of the strontium-substituted LaMnO3 have been determined as a function of the decomposition/oxidation temperature.
Abstract: The amorphous citrate process has been used to produce Mn2O3, Mn3O4, LaMnO3, SrMnO3 and strontium-substituted LaMnO3. The citrate-nitrate gels were dehydrated at 70‡ C to yield solid precursor materials. The decomposition/oxidation of the precursors have been studied using thermogravimetry and evolved gas analysis. The products of decomposition have been characterized by X-ray diffraction analysis, scanning electron microscopy and, in the case of the strontium-substituted LaMnO3, by analytical electron microscopy. The surface area and residual carbon content of the strontium-substituted LaMnO3 have been determined as a function of the decomposition/oxidation temperature. Both the process yield and compositional homogeneity of the strontium-substituted LaMnO3 have been shown to increase as the decomposition temperature increases. The residual carbon content has been shown to decrease as decomposition temperature increases. However, the surface areas of the powders decrease significantly as decomposition temperature increases. Consequently, it is evident that there is a conflict in the experimental conditions required for optimum yield, homogeneity and residual carbon content compared to those required for maximum surface area.
319 citations
136 citations
Journal Article•
TL;DR: In this article, the poudre de PbTiO 3 was incorporated into a gel polymere dielectrique to make composites flexible, and the gel polymer dielectric was used for the incorporation of Pb(NO 3 ) 2, TiCl 4, and NH 4 OH.
Abstract: Preparation d'une poudre de PbTiO 3 par precipitation d'une solution aqueuse de Pb(NO 3 ) 2 , TiCl 4 et NH 4 OH. Preparation de composites flexibles par incorporation de la poudre dans un gel polymere dielectrique. Proprietes dielectriques et piezoelectriques de ces composites
72 citations