A phase diagram of new high-T c superconductors

Cherenkov, V. A.

doi:10.1007/bf00635860

Cited by 4 publications

(3 citation statements)

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“…Despite the fact that the phase diagram of the YBCO system has been the subject of much investigation [5], controversies still exist, particularly near the melting temperature range. Our microstructural characterizations of the quenched melt of YBCO materials clearly show that the Ba-Cu-O-rich melt has a complex microstructure which changes with time and temperature in the melting range before quenching.…”

Section: Discussionmentioning

confidence: 99%

“…However, after holding the samples at 1040 • C or above for 20 h, the melt quenches, forming dendritic structures between BC1 and BC2. The dendrites suggest that the melt is homogeneous at 1040 • C (and higher temperatures) and that phase separation into BC1 and BC2 occurs below 1040 • C. If the initial melt of Y123 + 20 mol% Y211 were homogeneous from the start of melting (generally accepted to occur at about 1010-1020 • C [5]) we would expect that the homogeneity should remain and that dendritic patterns should always appear, independently of how long the melt is held above the melting temperature of Y123 before quenching. The melting of Y123 + 20 mol% Y211 must be quickly followed by crystallization of BC1, which rapidly segregates from the melt, or the initial melt occurs in the region of stability of BC1 + BC2 (containing some Y).…”

Section: Discussionmentioning

confidence: 99%

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Studies of the phase evolution of YBCO materials with different additives

Riches¹,

Alarco²,

Barry³

1998

Supercond. Sci. Technol.

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Y123 samples with varying amounts of added Y211, and have been melt processed and quenched from temperatures between and . The microstructures of the quenched samples have been characterized using a combination of x-ray diffractometry, optical microscopy, scanning electron microscopy, microprobe analysis, energy-dispersive x-ray spectroscopy and wavelength-dispersive x-ray spectroscopy. The Ba-Cu-O-rich melt undergoes complex changes as a function of temperature and time. A region of stability of (BC1) and (BC2) exists below in samples of Y123 + 20 mol% Y211. is stabilized by rapid quenching but appears to separate into BC1 and BC2 at lower quenching rates. and additions affect the distribution and volume fractions of the two Ba-Cu-oxide phases.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Studies of the phase evolution of YBCO materials with different additives

Riches¹,

Alarco²,

Barry³

1998

Supercond. Sci. Technol.

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“…. [14]. The non-stoichiometric phases then allow the oxygen content of the final compound to be tuned [15].…”

Section: Oxygen Dopingmentioning

confidence: 99%

Processing and superconducting properties of Hg_1-xRe_xBa₂Ca₂Cu₃O_8+delta

Sin

Odier

Cunha³

et al. 1999

Supercond. Sci. Technol.

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In this work we discuss one of the principal parameters to control for producing pieces of (Hg,Re)-1223 for device applications. The first prerequisite is the mixing of the cations which should be as good as possible and the degree of oxygen in the phase. The influence of the precursor oxygenation is discussed. It is shown that overdoped samples of (Hg,Re)-1223 have an increased irreversibility line. Finally the possibility of reprocessing sintered superconducting samples is shown, a very important aspect for the preparation of several ceramic electronic pieces.

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