Preparation and properties of spray dried precursor powder for melt-processed bulk YBCO ceramics

Lo, Wai; Cardwell, D. A.; Dung, S.L.; Barter, Richard G.

doi:10.1557/jmr.1996.0006

Cited by 33 publications

(11 citation statements)

References 22 publications

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“…Briefly, a Y1 6Ba2 3Cu3 308 5 .~ precursor powder (i.e. equivalent to a final phase composition of YBa2Cu307.6 + 0.3Y2BaCu05) was prepared by spray drying and subsequent calcination [12], [13]. The powder contained a substantial amount of submicron-sized particles which were confirmed to be predominantly YzBaCuOS in composition.…”

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confidence: 99%

Distribution of critical current density in large YBa/sub 2/Cu/sub 3/O/sub 7-δ/ grains fabricated using seeded peritectic solidification

Dewhurst

Cardwell

1997

IEEE Trans. Appl. Supercond.

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High quality large grain high T, superconducting ceramics offer enormous potential as 'permanent' magnets and in maginetic screening applications at 77K. This requires sample dimensions -cm with uniform high critical current densities of the order IO5 A/cmZ in applied magnetic fields of 1T. We report a study of the magnetic characterisation of a typical large YBazCusO7.6 grain, prepared by seeded peritectic solidification, and correlate the magnetically determined critical current density, Jc, with microstuctural features from different regions of the bulk sample. From this data we extract the temperature, field and positional dependence of the critical current density of the samples and the irreversibility line. We find that whilst the bulk sample exhibits a good Jc of order IO4 A/cm2 ('77K, IT), the local Jc is strongly correlated with the sample microstructure towards the edge of the sample and more severely at the centre of the sample by the presence of SmBazCu~O7.6 seed crystal. I . INTRODUCTIONThe irecent development of a variety of demonstrator devices that incorporate large grain, high temperature superconducting YBazCu307.6 (YBCO), such as magnetic bearings [1]-[5] and flywheel energy storage systems 651, [6] underlines the potential of this material for a range of permanent magnet-type engineering applications. These materials, which consist of a YBazCu3O7 6 (123) phase matrix with Y2BaCuOS (21 1) inclusions, are fabricated by a variety of melt processes based on peritectic solidification which occurs at around 1015°C in the YBCO system [7]. The flux trapping ability of YBCO, which generally forms the basis of these applications, depends fundamentally on the critical (current density, J,., of the material and the length scale over which it flows [8]. The presence of grain boundariies and intra grain domains can limit J, significantly and are clearly undesirable features of bulk YBCO. A main processing aim, therefore is to develop a large grain material with a high J, which flows over the entire grain dimension. Several microstructural features are commonly observed in bulk 'quasi' single crystalline YBCO material as the dimensions of the bulk sample exceed that of the seed crystal. 'These are (1) non-superconducting 21 1 inclusions in the 123 matrix, (2) platelets with thickness of about ten microns separating the bulk of the large grain along the YBCO &planes and (3) a cellular structure of the 123 matrix i n the plane perpendicular to the average c-axis of the 123 matrix. Manuscript received August 27, 1996. WL would like to acknowledge the support of the Croucher Foundation, EA Technology and British Nuclear Fuels Ltd. CDD would like to acknowledge MagneTek for the provision of a CASE Studentship and EPSRC and Fitzwilliam College for conference financial support.If SmBazCu307.~ seeds are used for the solidification processing of the YBCO grains, in contrast to SrTi03 seeds [7], Sm contamination of the 123 matrix occurs at positions close to the seed, resulting from the partial dissolution of the S...

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confidence: 99%

Distribution of critical current density in large YBa/sub 2/Cu/sub 3/O/sub 7-δ/ grains fabricated using seeded peritectic solidification

Dewhurst

Cardwell

1997

IEEE Trans. Appl. Supercond.

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“…Three batches of Nd-Ba-Cu-O powder were prepared by the spray drying process described in [8]. Briefly, this involved dissolving hydrolysed Nd(NO 3 ) 3 , Ba(NO 3 ) 2 and Cu(NO 3 ) 2 in 0.12 mol% dilute nitric acid with an overall cation stoichiometry of Nd:Ba:Cu = 1.6:2.3:3.3.…”

Section: Methodsmentioning

confidence: 99%

Effect of Corrosion Inhibitor, Benzotriazole, in Cu Slurry on Cu Polishing

Kim

Kang

Kim

et al. 2008

jjap

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Nd-Ba-Cu-O (NdBCO) precursor powder composed primarily of NdBa 2 Cu 3 O 7−δ (Nd-123) and 15 mol% Nd 4 Ba 2 Cu 2 O 10 (Nd-422) containing 0.1 wt% Au has been prepared by spray drying and subsequent calcination for the fabrication of bulk melt-processed ceramics. The addition of Au results in the lowering of key process parameters, such as the peritectic melting point and solidification temperatures by up to 30 • C. Additional doping of Au/NdBCO with 5 wt% Ag 2 O lowers these values further and has enabled the successful nucleation and limited growth of single grains under both air and reduced oxygen atmospheres using undoped NdBCO as a seed. The advantage of this self-seeded melt growth technique is that it avoids the lattice mismatch that results from the conventional use of a MgO seed.

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“…28,29 These pellets were sintered prior to melt processing to increase their density to 5.9 g͞cm 3 . 28,29 These pellets were sintered prior to melt processing to increase their density to 5.9 g͞cm 3 .…”

Section: Methodsmentioning

confidence: 99%

Anisotropic growth morphology and platelet formation in large grain Y–Ba–Cu–O grown by seeded peritectic solidification

Cardwell

Chow

1998

J. Mater. Res.

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The characteristic platelet-like structure of large grain superconducting Y-Ba-Cu-O fabricated using peritectic solidification techniques has been documented widely as a key microstructural feature of this material. The platelet formation mechanism is investigated via a detailed comparison of the difference in morphology of YBa 2 Cu 3 O 72d (123) growth fronts propagating along different lattice directions. The development of YBa 2 Cu 3 O 72d dendrites between the growth front and local Y 2 BaCuO 5 (211) particles is observed to be a key feature of the growth mechanism along all directions. Dendrites broaden rapidly for growth fronts propagating along the c-axis due to the enhanced growth rate of Y-Ba-Cu-O in the a-b plane to yield a uniform, regular growth morphology. Dendrite broadening is inhibited for grain growth along the a-b directions, however, due to the slower growth rate along the c-axis, which yields an irregular extended growth front. Growth along the a͞b direction commonly results in the formation of regions consisting of 123 dendrites which may connect 211 particles. Continued solidification of the 123 phase in such regions results in the development of platelet structures perpendicular to the crystallographic c-axis in the YBa 2 Cu 3 O 72d phase matrix which may impede the flow of current through the grain in the superconducting state.

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Preparation and properties of spray dried precursor powder for melt-processed bulk YBCO ceramics

Cited by 33 publications

References 22 publications

Distribution of critical current density in large YBa/sub 2/Cu/sub 3/O/sub 7-δ/ grains fabricated using seeded peritectic solidification

Distribution of critical current density in large YBa/sub 2/Cu/sub 3/O/sub 7-δ/ grains fabricated using seeded peritectic solidification

Effect of Corrosion Inhibitor, Benzotriazole, in Cu Slurry on Cu Polishing

Anisotropic growth morphology and platelet formation in large grain Y–Ba–Cu–O grown by seeded peritectic solidification

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