Title:
Grain-boundary chemistry and weak-link behavior of polycrystalline YBa[subscript 2]Cu[subscript 4]O[subscript 8]
Grain-boundary chemistry and weak-link behavior of polycrystalline YBa[subscript 2]Cu[subscript 4]O[subscript 8]
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Author(s)
Wang, Z. L. (Zhong Lin)
Brynestad, J.
Kroeger, D. M.
Sun, Y. R.
Thompson, J. R.
Williams, R. K.
Brynestad, J.
Kroeger, D. M.
Sun, Y. R.
Thompson, J. R.
Williams, R. K.
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Abstract
Magnetic-susceptibility and grain-boundary-chemistry data were obtained on dense YBa[subscript 2]Cu[subscript 4]O[subscript 8] (Y1:2:4) samples. Transmission-electron microscopy showed that the grain boundaries were free of second
phases and the dislocation density was low. Cation content, oxygen composition, and hole density were
determined by the combined techniques of nanoprobe energy-dispersive x-ray spectroscopy and
electron-energy-loss spectroscopy. A total of 25 pairs of grains was analyzed and the results indicated
that grain boundary and bulk compositions do not differ. The relative orientations of the crystallites
were determined, and the results show that a wide variety of misorientations was sampled. Almost all of
the grain boundaries were fully oxygenated and there are no hole deficiencies, but the magnetic susceptibility measurements showed that the material is granular weak linked. These results indicate that
Y 1:2:4 is a material in which clean, stoichiometric boundaries still form weak links.
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Date Issued
1993-10
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