Material Specification for Tl:2212; [Tl-Ba-Ca-Cu-O]
Process: Solid State Reaction
Notes: "Tl2O3, BaO2, CaO and CuO powder were mixed in an inert atmosphere and pressed into a pellet. The gross composition was Tl2Ba2Ca2Cu3O10. The pellet was placed in a long alumina crucible together with, but separated from, Tl2O3 powder. The crucible with lid was placed in a silica tube with flowing O2. The temperature was kept at 750 °C for 2 h, followed by 24 h at 860 °C. The pellet was re-ground and re-pressed, then reheated in flowing O2 for 16 h at 880 °C, followed by 700 °C for 4 h, and 550 °C for 2 h, before finally being ground to a powder."
Formula: Tl2Ba2CaCu2O8
Informal Name: Tl:2212
Chemical Family: Tl-Ba-Ca-Cu-O
Chemical Class: Oxide
Structure Type: Polycrystalline
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:
Crystallography for Tl:2212; [Tl-Ba-Ca-Cu-O]
| Crystal System: | Tetragonal |
| Formula Units per Cell: | 2 |
| Space Group: |
I4/mmm
|
Cell Parameters
| Occupancy () |
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| --- |
300 |
3.8558(1) |
-- |
29.2596(9) |
Atomic Coordinates
| Occupancy () |
Atom |
Temp
K
|
a-axis |
b-axis |
c-axis |
| 3.87(3) |
Tl |
300 |
0.5 |
0.5 |
0.2125(1) |
| 3.91(4) |
Ba |
300 |
0 |
0 |
0.1210(1) |
| 2.15(3) |
Ca |
300 |
0 |
0 |
0 |
| 3.92(4) |
Cu |
300 |
0.5 |
0.5 |
0.0551(1) |
| 8 |
O(1) |
300 |
0 |
0.5 |
0.0528(1) |
| 4.08(4) |
O(2) |
300 |
0.5 |
0.5 |
0.1447(1) |
| 4.34(5) |
O(3) |
300 |
0.6256(21) |
0.5 |
0.2806(2) |
Measurement Method: Neutron diffraction
"About 3 g of the sample was sealed in an aluminum can, and high resolution neutron powder data collected on D2B at ILL Grenoble with a wavelength of 1.5967 σ to 2θ = 165° in steps of 0.025°. Each point was averaged over 8 different detectors, with a total collection time of 12 h. ... Data were also collected at a wavelength of 3 σ on D1A, to check that there was no deviation from tetragonal symmetry. An early version of the Rietveld profile refinement program was used... The background level was measured manually, and small regions containing peaks from the Al container or impurity phase excluded."
Cautions: Evaluated Data
