Material Specification for Tl:221; [Tl-Ba-Cu-O]
Process: Solid State Reaction
Notes: "Samples of the compound Tl-2201 were prepared using a solid state reaction. In procedure #1, stoichiometric proportions of Tl2O3, BaO2 and CuO were ground to a fine powder and heated at 650 °C for (about) 12 h reground and pressed into pellets. The pellets were then heated in an open container for 5 min at 850 °C in flowing oxygen. In a variant preparation procedure (#2), samples were prepared from the same starting compounds except BaCO3 was substituted for BaO2 and the powder was not heated before being pressed into a pellet. In both cases the samples were rapidly cooled outside the furnace."
Formula: Tl2Ba2CuO6-x
Informal Name: Tl:221
Chemical Family: Tl-Ba-Cu-O
Chemical Class: Oxide
Structure Type: Polycrystalline
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:
Crystallography for Tl:221; [Tl-Ba-Cu-O]
| Crystal System: | Tetragonal |
| Formula Units per Cell: | |
| Space Group: |
|
Cell Parameters
|
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| 296 |
3.87 |
3.87 |
23.238 |
Measurement Method: X-ray diffraction
"Powder X-ray diffraction (using CuKα radiation)" was used to determine the tetragonal unit cell parameters." No additional measurement details were noted.
Cautions: Unevaluated Data
Critical Temperature for Tl:221; [Tl-Ba-Cu-O]
| Process Number () |
Critical Temperature (K) |
| 1 |
73 |
| 2 |
30 |
Measurement Method: Electrical resistance
"The resistance was measured by a four-probe method using an APD Cryogenics (SCC) closed cycle refrigerator." The temperature of zero resistance was used as the critical temperature. No additional measurement details were noted.
Cautions: Evaluated Data
Thermoelectric Power for Tl:221; [Tl-Ba-Cu-O]
| Process Number () |
Temperature (K) |
Thermoelectric Power (µV/K) |
| 1 |
80 |
0.04 |
| 1 |
84 |
0.21 |
| 1 |
84 |
0.60 |
| 1 |
88 |
1.32 |
| 1 |
92 |
1.57 |
| 1 |
108 |
0.68 |
| 1 |
120 |
0.04 |
| 1 |
130 |
-0.30 |
| 1 |
146 |
-0.68 |
| 1 |
162 |
-1.06 |
| 1 |
182 |
-1.45 |
| 1 |
194 |
-1.87 |
| 2 |
80 |
-2.04 |
| 2 |
96 |
-2.77 |
| 2 |
121 |
-3.54 |
| 2 |
134 |
-3.93 |
| 2 |
154 |
-4.67 |
| 2 |
177 |
-5.48 |
| 2 |
185 |
-5.82 |
Measurement Method: Thermopower method
"The TEP was measured using a two heater system mounted in an evacuated chamber that was immersed in LN
2. After cooling to 77 K the chamber was filled with He gas which formed thermal contact between the sample and the chamber walls and served to damp thermal oscillations. Samples were cut into rectangles 10 mm x 5 mm x 2 mm and clamped lengthwise between spring loaded copper blocks. Good thermal contact was made using insulating sapphire. The average temperature of the samples was controlled to within 0.05 K and raised in steps of 2 K at the rate of... 0.2 K/min. The difference in temperature between the ends of the sample ranged from 3 K to 8 K. The system was calibrated using a p-type sample of the 2223 phase Tl based superconductor."
Cautions: Evaluated Data
Digitized data were obtained from Figures 2 and 3 of the paper.
