Comparison of fully-reacted and partly-reacted Bi2Sr2CaCu2Oy precursor powders

Sunli, Huang; Dew‐Hughes, D.; Fossheim, K.

doi:10.1016/s0921-4534(97)01389-0

Cited by 8 publications

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“…These studies propose requirements on stoichiometry, phase purity, homogeneity and carbon content of Bi2212 precursors in the green wire. Yet, far fewer studies have discussed the effect of precursor stoichiometry on wire performance [23,36], and most of those either focused solely on the synthesis process and properties of Bi2212 bulk materials [24,[37][38][39][40][41][42] or studied precursor properties by comparing superconducting tapes/ thick films that had varying methods, geometries and substrates [10,19,29,43,44]. Furthermore, recent over-pressure (OP) processing has effectively reduced gross microstructural porosity in Bi2212 wire, resulting in greatly increased critical current density ( J c ) [45].…”

Section: Introductionmentioning

confidence: 99%

High critical current density Bi₂Sr₂CaCu₂O_x/Ag wire containing oxide precursor synthesized from nano-oxides

Zhang

Johnson

Naderi

et al. 2016

Supercond. Sci. Technol.

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Bi2Sr2CaCu2Ox (Bi2212)/Ag-alloy wires are manufactured via the oxide-powder-in-tube route by filling Ag/Ag-alloy tubes with Bi2212 oxide precursor, deforming into wire, restacking and heat treating using partial-melt processing (PMP). Recent studies propose several requirements on precursor properties, including stoichiometry, chemical homogeneity, carbon content and phase purity. Here, nanosize oxides produced by nGimat’s proprietary NanoSpray CombustionTM process are used as starting materials to synthesize Bi2212 oxide precursors via solid-state calcination. Oxide powders for wire fill (precursor powder) with precisely controlled stoichiometry and chemical homogeneity containing over 99 vol% of single Bi2212-phase are synthesized. Alkaline-earth cuprate are found to be the only impurity phase in the precursor powders. Phase transformation, carbon release and grain growth during calcination are studied through a series of quench studies. Effects of particle size, surface area, stoichiometry, chemical homogeneity and microstructures of the starting materials on Bi2212 formation and wire transport properties are discussed. Small particle size, high surface area and short diffusion length of the starting materials result in a rapid and homogeneous phase transformation to Bi2212, along with an early and rapid carbon release. The residual carbon in the precursor powder is between 50 and 90 ppm. The strong dependence of transport Jc on precursor stoichiometry indicates that compositional variations within precursor powders should be less than 1.5 mol%. Two Bi-rich and Ca-deficient stoichiometries give higher wire transport critical current density, with the highest being 2520 A mm−2 (4.2 K, 5 T) after 1 bar PMP and 4560 A mm−2 (4.2 K, 5 T) after 100 bar overpressure (OP) processing. The low residual carbon content results in smaller and fewer voids within an OP-processed wire filament. Bi-rich and Ca-deficient stoichiometries and small compositional variations within precursor powders may be a method for engineering uniformly-distributed and high-density Bi2201 intergrowths within Bi2212 grains after PMP.

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Section: Introductionmentioning

confidence: 99%

High critical current density Bi₂Sr₂CaCu₂O_x/Ag wire containing oxide precursor synthesized from nano-oxides

Zhang

Johnson

Naderi

et al. 2016

Supercond. Sci. Technol.

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“…Za prahova zadatog sastava -Bi1. [195], dok је ovaj period nesto kracj kod prahova doЬijenjh koprecipitacjjom oksalata metala [196]. [198,199].…”

Section: Reakciono Rasprsivanje: Dirigovana Sinteza Nanostrukturnih Ounclassified

Conducted synthesis of nanostructured oxide powders with tailored properties

Mančić¹

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Development of advanced materials, together with the efforts invested in the optimization of their cuпent properties today result in the opening of а new fiel d of the deSign of ultra fine structure materials. Nanostructured materials with new and improved properties could Ье prepared through different techniques. Investigations presented here are focused on conducted synthesis ofnanostructured oxide powders in ZnCђ04 and Вi1.8РЬо2SђСа2Сиз Ох systems using the spray pyrolysis method. The main emphasis is on controlled evolution of specific phases characterized with properties suitaЬle for potential technical application. The strategy used is the result of methodology development from the viewpoint of estaЬlishing synthesis-structureproperties relations. Because of that, investigation of phase thermal staЬility, particle morphology-shape, size and agglomeration, crystal structure-grain boundary and defects concentration, homogeneity of chemical composition are of special interest. As а result of ZnC[20 4 powder conduction synthesis using spray pyrolysis of nitrate salts, spherical particles with uniform size around 470nm are obtained. Synthesized dense particles are uniform in shape and posses small differences in crystallinity and stoichiometry Effect of droplet/particle residence time on fmal powder morphology is estaЬlished through investigation of precursor decomposition, nucleation and growth of primary crystallites in nanoporous precipitated particles. It was shown that increase of the residence time indicates growth of nanocrystallites with mean sizes around 40nm leading to dense particle evolution. Also, formation of а spinel phase with high homogeneity and uniformity of chemical composition in all produced samples are characterized with the cation ratio of Zn/Cr=0.68. Constant mismatchшg in stoichiometry from the assigned value, as well as additional changes in particle morphology after their thermal treatment at 1 000°С (2h) is the consequence of ZnO dissolution in а spinel cell and is explained Ьу а model, which is based on computing of crystal surface formation energy and surfaces attachment energy. It was shown that the achieved particle morphology is predicted Ьу а model as an unique surface structure which posses improved sensor and catalytic properties. Specific phase development in the Bir. sPbo.2Sr2Ca2CuзOx system synthesized through conducted spray pyrolysis process is estimated from the viewpoint of nitrate precursor modification due to in situ existence of а thermal source in every droplet. The effect of controlled hydrolysis as well as thermal explosion of droplets on 2223 phase formation is defined based on the investigation of salt precipitation and the decomposition process. Additional reduction in particle size from 400 to 140nm and maintenance of structural and compositional homogeneity result in intensification of different phase conversions and orthorhomЬic 2223 phase formation. Coexistence of both, 2212 and 2223 phase is determined for all samples. Their further conversion is favorize...

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Influence of processing parameters of partial-melting process on phase assemblage, microstructure and superconducting properties of Bi-2212 bulk material

Marinković

Xia

Serra

et al. 2005

Materials Chemistry and Physics

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Comparison of fully-reacted and partly-reacted Bi2Sr2CaCu2Oy precursor powders

Cited by 8 publications

References 5 publications

High critical current density Bi₂Sr₂CaCu₂O_x/Ag wire containing oxide precursor synthesized from nano-oxides

High critical current density Bi₂Sr₂CaCu₂O_x/Ag wire containing oxide precursor synthesized from nano-oxides

Conducted synthesis of nanostructured oxide powders with tailored properties

Influence of processing parameters of partial-melting process on phase assemblage, microstructure and superconducting properties of Bi-2212 bulk material

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Comparison of fully-reacted and partly-reacted Bi2Sr2CaCu2Oy precursor powders

Cited by 8 publications

References 5 publications

High critical current density Bi2Sr2CaCu2Ox/Ag wire containing oxide precursor synthesized from nano-oxides

High critical current density Bi2Sr2CaCu2Ox/Ag wire containing oxide precursor synthesized from nano-oxides

Conducted synthesis of nanostructured oxide powders with tailored properties

Influence of processing parameters of partial-melting process on phase assemblage, microstructure and superconducting properties of Bi-2212 bulk material

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High critical current density Bi₂Sr₂CaCu₂O_x/Ag wire containing oxide precursor synthesized from nano-oxides

High critical current density Bi₂Sr₂CaCu₂O_x/Ag wire containing oxide precursor synthesized from nano-oxides