Material Specification for La:21; [La(Ba)-Cu-O]
Process: Solid State Reaction
Notes: "Powder specimens... were prepared by the solid-state reaction of a mixture of predried La2O3, BaCO3 and CuO. The powders were pressed into pellets, calcined at 900 °C for 24 h and then sintered at 1050 °C in air for several days with frequent grindings. The pellets were ground and finally annealed at 500 °C for 24 h in flowing O2 gas."
Formula: La2-xBaxCuO4
Informal Name: La:21
Chemical Family: La(Ba)-Cu-O
Chemical Class: Oxide
Structure Type: Polycrystalline
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:
Crystallography for La:21; [La(Ba)-Cu-O]
| Crystal System: | |
| Formula Units per Cell: | |
| Space Group: |
|
Cell Parameters
| x of Bax (formula units) |
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| 0.03 |
115 |
5.3407(1) |
5.4054(1) |
13.1554(3) |
| 0.08 |
115 |
5.34141(9) |
5.38390(9) |
13.2060(2) |
| 0.125 |
115 |
5.33915(9) |
5.35882(9) |
13.2414(2) |
| 0.17 |
115 |
3.77993(6) |
-- |
13.2885(2) |
| 0.24 |
115 |
3.77866(7) |
-- |
13.3235(3) |
Atomic Coordinates
| x of Bax (formula units) |
Atom |
Temp
K
|
a-axis |
b-axis |
c-axis |
| 0.03 |
La/Ba |
115 |
0 |
-0.0077(3) |
0.3611(1) |
| 0.03 |
Cu |
115 |
0 |
0 |
0 |
| 0.03 |
O(1) |
115 |
0.25 |
0.25 |
0.0077(2) |
| 0.03 |
O(2) |
115 |
0 |
0.0366(3) |
0.1834(2) |
| 0.08 |
La/Ba |
115 |
0 |
-0.0063(3) |
0.36107(9) |
| 0.08 |
Cu |
115 |
0 |
0 |
0 |
| 0.08 |
O(1) |
115 |
0.25 |
0.25 |
0.0064(2) |
| 0.08 |
O(2) |
115 |
0 |
0.0301(4) |
0.1828(1) |
| 0.125 |
La/Ba |
115 |
0 |
-0.0047(4) |
0.36086(8) |
| 0.125 |
Cu |
115 |
0 |
0 |
0 |
| 0.125 |
O(1) |
115 |
0.25 |
0.25 |
0.0051(2) |
| 0.125 |
O(2) |
115 |
0 |
0.0222(5) |
0.1822(2) |
| 0.17 |
La/Ba |
115 |
0 |
0 |
0.3607(1) |
| 0.17 |
Cu |
115 |
0 |
0 |
0 |
| 0.17 |
O(1) |
115 |
0 |
0.5 |
0 |
| 0.17 |
O(2) |
115 |
0 |
0 |
0.1817(2) |
| 0.24 |
La/Ba |
115 |
0 |
0 |
0.3603(1) |
| 0.24 |
Cu |
115 |
0 |
0 |
0 |
| 0.24 |
O(1) |
115 |
0 |
0.5 |
0 |
| 0.24 |
O(2) |
115 |
0 |
0 |
0.1811(2) |
Measurement Method: Neutron diffraction
"The neutron diffraction experiments were made using the multidetector high-resolution powder diffractometer installed at the high flux isotope reactor (HFIR) at the Oak Ridge National Laboratory. The (115) reflection of Ge was used as the monochromator, and the neutron wavelength was 1.4000 σ. This instrument has Soller-slit collimators of 12' and 20' located before and after the monochromator crystal, and collimators of 6' in front of each of the instrument's 32 detectors. The specimen was placed in a crylindrical vanadium holder of thickness 0.05 mm, and enclosed in an aluminum can filled with helium exchange gas. The measurements were carried out at temperatures down to 15 K using a standard closed-cycle refrigerator. The data analysis was performed using GSAS, a computer code that employs the Rietveld full-pattern analysis method to refine crystal structures."
Cautions: Evaluated Data
Critical Temperature for La:21; [La(Ba)-Cu-O]
| x of Bax (formula units) |
Critical Temperature (K) |
| 0.03 |
0 |
| 0.08 |
25 |
| 0.125 |
4 |
| 0.17 |
26 |
| 0.24 |
0 |
Measurement Method: Susceptibility method
"The superconducting properties for these compounds were examined at temperatures down to 1.8 K by the AC induction method. For x = 0.125, DC susceptibility was measured at temperatures down to 4.2 K using a magnetic balance. The superconducting transition temperatures of the sample under study were determined by the onset of the diamagnetic susceptibility." No additional measurement details were noted.
Cautions: Unevaluated Data
