Material Specification for Tl:2234; [Tl-Ba-Ca-Cu-O]
Process: Solid State Reaction
Notes: The authors cite T. Kaneko et al., J. Appl. Phys., Vol. 71, 2347 (1992), and summarize the procedure as follows. "Single superconducting phase 2234 was synthesized... Tl2O3 (99.9%), BaO2, CaO and CuO (99.99%) were mixed in the metal ratio 1.5:2.0:3.5:4.0 and thoroughly ground together in an agate pestle and mortar. The loose mixture was transferred to a gold tube which was crimped firmly shut. The tube was heated at 860 °C for 10 h in air and quenched to room temperature; longer or shorter reaction times produce less pure product."
Formula: Tl2Ba2Ca3Cu4O12
Informal Name: Tl:2234
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:2234; [Tl-Ba-Ca-Cu-O]
| Crystal System: | Tetragonal |
| Formula Units per Cell: | |
| Space Group: |
I4/mmm
|
Cell Parameters
| Occupancy () |
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| -- |
296 |
3.84877(5) |
-- |
42.0494(9) |
Atomic Coordinates
| Occupancy () |
Atom |
Temp
K
|
a-axis |
b-axis |
c-axis |
| 0.82(1) |
Tl |
296 |
0.5 |
0.5 |
0.2243(1) |
| -- |
Ba |
296 |
0.0 |
0.0 |
0.1613(1) |
| -- |
Cu(1) |
296 |
0.5 |
0.5 |
0.0364(2) |
| -- |
Cu(2) |
296 |
0.5 |
0.5 |
0.1134(3) |
| -- |
Ca(1) |
296 |
0.0 |
0.0 |
0.0 |
| -- |
Ca(2) |
296 |
0.0 |
0.0 |
0.0764(3) |
| -- |
O(1) |
296 |
0.5 |
0.0 |
0.0374(7) |
| -- |
O(2) |
296 |
0.5 |
0.0 |
0.1126(8) |
| -- |
O(3) |
296 |
0.5 |
0.5 |
0.1766(11) |
| 0.25 |
O(4) |
296 |
0.606(24) |
0.5 |
0.2664(14) |
Measurement Method: X-ray diffraction
"Powder X-ray diffraction using a Siemens D5000 diffractometer employing CuKα
1 (was used)... over a 14 h period in the two theta range 20-110° with a step size of 0.02°. Analysis of this data was undertaken using a recent version of the... package, DBW9006PC, allowing simultaneous multi-profile refinement taking all reflections from the impurities into account."
Cautions: Evaluated Data
