Material Specification for La:21; [La(Sr)-Cu-O]
Process: Solid State Reaction
Notes: "Black polycrystalline powders of... LSCO, were prepared by the following procedure. An aqueous solution containing 2.5 g of Cu(NO3)2•3H2O (10.3 mmol), 8.29 g of La(NO3)3•6H2O (19.1 mmol), and 0.334 g of Sr(NO3)2 (1.58 mmol) was neutralized to pH 7-8 by slow addition of a KOH (0.98 g in 15 mL of H2O) solution. The hydroxy carbonates of La/Sr/Cu were precipitated by mixing with a K2CO3 (6.89 g, 50 mmol) solution and were washed thoroughly with distilled water until the filtrate gave a pH around 8. The blue powders obtained were dried at 140 °C overnight and further calcined at 900 °C for 3 h to give 4.16 g of black powder (quantitative yield)... a platinum crucible charged with 66 mg of the LSCO compound and 210 mg of a lead oxide and lead dioxide mixture (200 mg: 10 mg) was heated at 1050 °C in air. Approximately 77 mg of product and remaining flux were obtained after 65 h."
Formula: La1.85Sr0.15CuO4
Informal Name: La:21
Chemical Family: La(Sr)-Cu-O
Chemical Class: Oxide
Structure Type: Single Crystal
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:
Density (mass) for La:21; [La(Sr)-Cu-O]
Measurement Method: X-ray diffraction
"X-ray diffraction data were collected on a Nicolet P3/F diffractomer... Diffraction data (θ-2θ scans, MoKα radiation, graphite monochromator,... (wavelength) = 0.7107 σ) were collected in the range 4°<2ϑ<70°, and 1753 data from all octants were corrected for absorption... and averaged... to yield 160 unique reflections... Full-matrix least-squares refinement with anisotropic temperature factors and isotropic extinction correction (was used)."
Cautions: Evaluated Data
Crystallography for La:21; [La(Sr)-Cu-O]
| Crystal System: | Tetragonal |
| Formula Units per Cell: | 2 |
| Space Group: |
I4/mmm
|
Cell Parameters
|
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| 296 |
3.7966(7) |
-- |
13.186(4) |
Atomic Coordinates
| Atom |
Temp
K
|
a-axis |
b-axis |
c-axis |
| La/Sr |
296 |
0.0000 |
0.0000 |
0.36094(2) |
| Cu |
296 |
0.0000 |
0.0000 |
0.0000 |
| O(1) |
296 |
0.0000 |
0.5000 |
0.0000 |
| O(2) |
296 |
0.0000 |
0.0000 |
0.1825(3) |
Measurement Method: X-ray diffraction
"X-ray diffraction data were collected on a Nicolet P3/F diffractomer... Diffraction data (θ-2θ scans, MoKα radiation, graphite monochromator,... (wavelength) = 0.7107 σ) were collected in the range 4°<2ϑ<70°, and 1753 data from all octants were corrected for absorption... and averaged... to yield 160 unique reflections... Full-matrix least-squares refinement with anisotropic temperature factors and isotropic extinction correction (was used)."
Cautions: Evaluated Data
Critical Temperature for La:21; [La(Sr)-Cu-O]
| Critical Temperature (K) |
| 8.7 ± 0.3 |
Measurement Method: T
c measurement
"The individual crystals were too small to attach leads for a four-probe conductivity measurement or for inductive measurements on a single-crystal specimen. However, superconductivity was detected by rf penetration depth measurements at 500 kHz in a 1.5-mg sample consisting of many crystal specimens. This sample gave an onset temperature for superconducivity... of 8.5-9.0 K, a broad transition, and a low signal response (increase in sesonant frequency)."
Cautions: Unevaluated Data
