was discovered in 1987. It was the first high temperature
superconductor at temperatures exceeding that of liquid
nitrogen boiling point (77 K). It shows a critical temperature
of Tc = 90 K. YBa2Cu3O7-d or so-called Y-123 powders with
99.9% purity are available. They are useful for bulk applications:
melt textured ceramics (Top-seeding growth, Bridgman bars),
polycrystalline pellets, etc.
Carbon content: £ 300 ppm
or so-called "green phase" is an additive customarily added
to Y-123 superconducting ceramics. The fact that this phase
does not become superconducting and its compatibility with
Y-123 makes it appropriate for incorporing precipitates
in the Y-123 ceramics. This second-phase inclusions enhance
critical current density as they act as strong pinning centers.
In addition, mechanical toughness is improved due to limitation
of fractures in the Y-123 matrix.
Y-211 with 99.9% purity powders are available.
Ba2Ca2Cu3O7 is a widely used precusor powder for preparation
of Tl-1223, Tl-2223, Hg-1223 and other high-Tc superconductors.
Addition of high-valence dopants is common practice: Pb,
V, Mo, Re, ... It consists of a multiphasic mixture in the
complex system Ba-Ca-Cu-O. Ba2Ca2Cu3O7 99.9% powders are
available. According to specific compositional requirements,
metal dopants can be added.
Low carbon content
precursor powders are used for preparation of Bi-2223, Tl-1223,
Hg-1223 and other Sr-based high-Tc superconductors. As in
the case of Ba2Ca2Cu3O7, addition of high-valence dopants
is common practice: Pb, Cr, V, etc. Sr2Ca2Cu3O7 99.9% powders
to specific compositional requirements, metal dopants can
Low carbon content.
copper oxide (II) powders are available for advanced ceramic
materials: high-temperature superconducting cuprates, targets
for sputtering devices, etc.
barium carbonate powders are available for advanced ceramic
materials: high-temperature superconducting cuprates, barium
titanate, barium zirconate, sputtering targets, etc.