Material Specification for Y:123; [Y-Ba-Cu-O]
Process: Flux Growth
Notes: "The YBa2Cu3O7-δ crystals were grown using a "self-flux" technique. First, stoichiometric amounts of Y2O3, BaCO3, and CuO were ground and sintered at 900 °C for 4 days with 3 intermediate grindings to form a polycrystalline precursor of YBa2Cu3O7-δ. Next, the precursor was mixed with extra BaCO3 and CuO in a molar ratio of 1:7:21 to form a flux. Finally, the mixture was placed in yttria-stabilized zirconia trays, heated slowly to 980 °C, cooled from 980 °C to 880 °C to room temperature at 100 °C per hour. This process yielded flat platelets of YBa2Cu3O7-δ single crystals embedded in the flux, approximately 1 mm x 1 mm x 100 µm in size, which were removed mechanically from the crucible. The crystals were then annealed in gold crucibles in a tube furnace at 420 °C for 10 days, under flowing high-purity oxygen, in order to fully oxygenate the crystals (δ about 0.05). ... The crystals were then detwinned... A uniaxial pressure of about 108 N/m2 was carefully applied to the crystal with a spring. The displacement of the spring was measured with a calibrated micrometer head attached to the press. The crystal under pressure was annealed at temperatures between 450 °C and 490°C for several hours. Preheated oxygen gas was supplied through a capillary quartz tube to maintain the oxygen content of the single crystal during the detwinning process. The uniaxial stress and oxygen supply were maintained as the crystal was cooled at 4 °C per minute to room temperature."
Formula: YBa2Cu3O7-x
Informal Name: Y:123
Chemical Family: Y-Ba-Cu-O
Chemical Class: Oxide
Structure Type: Single Crystal
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:
Critical Temperature for Y:123; [Y-Ba-Cu-O]
| Transition Width (K) |
Critical Temperature (K) |
| 2 |
90 |
Measurement Method: Magnetic susceptibility
"The crystals were characterized by magnetic susceptibility..." No additional measurement details were noted.
Cautions: Unevaluated Data
Penetration Depth for Y:123; [Y-Ba-Cu-O]
| Sample Number () |
Depth along a-axis (σ) |
Depth along b-axis (σ) |
Penetration Depth (σ) |
| 1 |
2360 |
1398 |
1900 |
| 2 |
4171 |
1424 |
2800 |
| 3 |
2668 |
1772 |
2200 |
| 4 |
1609 |
904 |
1300 |
| 5 |
1609 |
1139 |
1400 |
| 6 |
1942 |
1307 |
1600 |
| 7 |
2092 |
1749 |
1900 |
| 8 |
2271 |
1368 |
1800 |
Measurement Method: Josephson tunneling
The authors cite A.G. Sun et al., Phys. Rev. Lett., Vol. 72, 2267 (1994), and summarize the procedure as follows. "...Josephson tunnel junctions were fabricated... Each junction was rectangular in shape... with one dimension defined by epoxy and the other defined by the shadow mask trhough which the Ag diffusion barrier and the Pb stripe were evaporated... The sides of the rectangle were made so that they were parallel to either the a or b direction. The junction was put into a vacuum can with leads attached for four-point measurements, and cooled down quickly to 77 K with the help of He exchange gas. This was done within half an hour after the Ag and Pb deposition... Before the measurements, the exchange gas was pumped out of the vacuum can and the sample temperature was raised to about 120 K... with a heater on the sample stage. The vacuum can housing the sample was then immersed in liquid He in a cryogenic Dewar shielded with µ-metal, and the sample was cooled down (at a rate of 1 K/min)... After 2 h when the sample had reached about 30 K... exchange gas was transferred into the vacuum can to reduce the temperature to 4.2 K. The sample was then cycled a few times above the T
c of Pb to expel any trapped flux in the Pb. ... The magnetic field was applied with a Helmhotz coil inside the µ-metal shield, with the field lines parallel to the CuO
2 planes. By rotating the sample around the c axis, we were able to align the field along different crystalline directions within the CuO
2 plane. Because the penetration depths in different directions are defined according to the directions of the screening current in the superconductor (the penetration depth in the a-axis direction) was extracted from the I
c(B) pattern when the magnetic field was applied along the b direction and vice versa."
Cautions: Evaluated Data
"We do not yet understand why we observe such a variation from sample to sample, but we suspect the variation in the measured values of the penetration depths comes from the difference in oxygen doping and disorder in the YBa
2Cu
3O
7-δ crystals, and the resulting chain integrity and planar carrier concentration."
The "Penetration Depth" in the data table is the average of the penetration depths along the a and b axes.
