Chemical inhomogeneities in YBaCuO produced by conventionnal sintering

Odier, P.; Dubois, B.; Gervais, Monique; Douy, André

doi:10.1016/0025-5408(89)90003-2

Cited by 19 publications

(5 citation statements)

References 15 publications

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“…Until recently little effort was directed at developing and using new types of precursors. Metal acetate, chloride, nitrate, lactate, citrate, and oxalate solutions were used extensively to produce a wide variety of materials (Akashi et al, 1967;Kanapilly et al, 1970;Suyama and Kato, 1982;Chess et al, 1983;Gardner and Messing, 1984;Imai et al, 1984;Kato and Hirata, 1985;Sproson et al, 1986;Ivers-Tiffee and Seitz, 1987;Seitz et al, 1987;Kodas et al, 1988Kodas et al, , 1989aPebler and Charles, 1988;Setaka et al, 1988;Dubois et al, 1989;Odier et al, 1989;Rossetti et al, 1989;Gadalla and Yu, 1990a, b;Pebler, 1990;Ortega et al, 1991). These precursors have the advantage of being inexpensive.…”

Section: Materials Produced By Spray Pyrolysismentioning

confidence: 99%

Aerosol Processing of Materials

Gurav,

Kodas,

Pluym

et al. 1993

Aerosol Science and Technology

381

225

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Recent advances in aerosol generation of materials are reviewed. Gas-to-particle and spray processes (spray pyrolysis) for powder generation and various routes for film generation are discussed from the experimental and theoretical perspectives. The range of materials generated by these routes has increased in recent years to include fullerenes and ceramic superconductors. Many metals and various oxide and nonoxide ceramics have also been added to the list of materials generated by gas-phase routes. Established aerosol routes such as vapor condensation have found widespread applications for generation of nanophase materials. The formation of quantum dots via aerosol approaches has also been demonstrated. The theoretical understanding of gas-to-particle conversion routes has advanced to include the finite rate of particle fusion or sintering occurring after collisions of particles. The modeling of spray pyrolysis systems has provided insight into the control of particle morphology and reactor design. In this review, these recent developments in aerosol generation of powders and films via gas-phase and spray routes are discussed with an emphasis on the material chen~istries involved and the synthesis of nanophase materials.

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Section: Materials Produced By Spray Pyrolysismentioning

confidence: 99%

Aerosol Processing of Materials

Gurav,

Kodas,

Pluym

et al. 1993

Aerosol Science and Technology

381

225

View full text Add to dashboard Cite

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“…One possible simplification is the use of a solution of the cationic salts in which an intimate mixing of the components is produced by different techniques: the acetate route, coprecipitation, freeze-drying, etc, which result in a better degree of mixing, although some microsegregation can nonetheless appear [3]. These difficulties can also be overcome by quick solvent evaporation using spray drying or pyrolysis techniques.…”

Section: Introductionmentioning

confidence: 99%

Synthesizing the Y-123/Y-211 composite by the PVA method

Serradilla

Calleja²,

Capdevila

et al. 2002

Supercond. Sci. Technol.

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A polymerized organic–inorganic synthesis of a mixture containing 69% Y-123, 30% Y-211, 1% CeO2 in weight has been studied with the aid of polyvinylic alcohol (PVA). The advantages of this method are (a) avoidance of extensive and repetitive firing steps and (b) no need for mechanical mixing of components. By heating the solution of stoichiometric quantities of the nitrate salts, a viscous gel is obtained which turns into an aerogel by subsequent heating. The resulting aerogel was calcined in a single step and the powder was used to prepare Y-123/Y-211 composite monodomain rods by the vertical Bridgman solidification technique. Characterization of both powders and grown monodomains have been performed. Fine and dispersed Y-211 phase distribution was successfully achieved. Finally, magnetic measurements were performed by SQUID magnetometry.

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“…La deuxième méthode, II, vise l'obtention de particules sphériques et de granulométrie ajustée. Elle consiste en la décomposition thermique contrôlée d'un brouillard précurseur d'YBaCuO obtenu par ultra-sons [9]. Le précurseur liquide est identique à celui utilisé dans la méthode I. Dès 835 °C, on forme la phase YBaCuO qu'un refroidissement lent rend orthorhombique avec les propriétés supraconductrices recherchées [10].…”

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“…1). De même l'examen de l'évolution des microstructures entre 900° et 930 °C est conforme à ce mécanisme : la croissance granulaire est dans cette gamme de température extrêmement rapide et les fractures présentent des faciès à l'aspect amorphe [9].…”

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“…Une troisième transition se produit à 1 240 °C, elle correspond à la fusion péritectique du composé (211) qui se décompose alors en Y203 + liquide. La transition à 935 °C est corrélée avec une perte de masse significative [9] (départ d'oxygène), elle conditionne pour beaucoup le frittage du composé YBa2CU307 -, et son homogénéité chimique, voir figure 2 et référence [18].…”

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