ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Some unexpected chemistry will be discussed which occurs during the production of highT c superconductors by an oxalate route. Evaporation (rather than filtration) of a 1∶2∶3 Y∶Ba∶Cu nitrate solution containing excess oxalic acid was done, in order to make sure that the solid had the same composition as the solution. It was assumed that the removal of water and nitric acid by vacuum would quantitatively yield the salts as oxalates. Surprisingly, the evaporation changed what was initially a homogeneous, but off-composition, material into a rather inhomogeneous material. During the evaporation, the yttrium and barium were apparently redissolved from their initial form as submicrometre particles containing all three metals. They were redeposited as 10–100 μm rectangular and octahedral crystals. However, this material yields very good superconductors upon simple grinding and heat treatment as measured by conductivity and a.c. induction.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01130129
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