Material Specification for Hg:1223; [Hg(Tl)-Ba-Ca-Cu-O]
Process: Solid State Reaction
Notes: The authors cite G.F. Sun et al., Phys. Lett. A, Vol. 192, 122 (1994), and summarize the procedure as follows. "Briefly, a nominal Ba2Ca2Cu3O7 precursor was prepared first. HgO (99.9%) and Tl2O3 (99.99%) were mixed with the precursor and ground in a plastic bag filled with N2 gas. The cation ratio of (Hg1-xTlx)/Ba/Ca/Cu was 1223, where x = 0, 0.2. The ground powder was then pressed into rods of 6 mm in diameter and 15 mm in length. The pressed rods were put inside a quartz tube, evacuated and sealed. The sealed quartz tube was placed in a high-temperature oxygen-proof steel cylindrical container. A tube furnace was preheated to 860 °C. The container with the contents was then introduced into the furnace and kept at 860 °C for 400 min. At that time the furnace power was turned off and the content was allowed to cool to room temperature. After the sintering, the sample was annealed in O2 at 500 °C for 10 h."
Formula: Hg1-xTlxBa2Ca2Cu3O8.33
Informal Name: Hg:1223
Chemical Family: Hg(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 Hg:1223; [Hg(Tl)-Ba-Ca-Cu-O]
| Crystal System: | Tetragonal |
| Formula Units per Cell: | |
| Space Group: |
P4/mmm
|
Cell Parameters
|
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| 296 |
3.8489(1) |
-- |
15.816(1) |
| 10 |
3.8472(2) |
-- |
15.801(2) |
Atomic Coordinates
| Atom |
Temp
K
|
a-axis |
b-axis |
c-axis |
| Hg/Tl |
296 |
0 |
0 |
0 |
| Ba |
296 |
0 |
0 |
0.1754(8) |
| Ca |
296 |
0.5 |
0.5 |
0.399(1) |
| Cu(1) |
296 |
0 |
0 |
0.5 |
| Cu(2) |
296 |
0 |
0 |
0.3003(7) |
| O(1) |
296 |
0 |
0.5 |
0.5 |
| O(2) |
296 |
0 |
0.5 |
0.3021(6) |
| O(3) |
296 |
0 |
0 |
0.1199(9) |
| O(4) |
296 |
0.5 |
0.5 |
0 |
Measurement Method: Neutron diffraction
"Neutron powder diffraction data... were collected at room temperature and at 10 K using the HB4 high-resolution powder diffractometer at the High-Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. The HB4 instrument has a Ge(115) monochromator which, when 2θ=80°, selects an incident neutron beam wavelength of 1.4177 σ determined on the basis of unit-cell refinements for a Si powder standard. Soller slit collimators of 12' and 20' are positioned before and after the monochromator crystal, respectively. An array of 32 equally spaced (2.7°)
3He detectors, each with a 6' mylar foil collimator, can be step scanned over a range of up to 40° for scattering angles between 11° and 135°. The powdered sample (2 g) was placed in a cylindrical Al can (4 mm in diameter and 5 cm long) and the detector scanned over a 2θ range of 11° to 135° in steps of 0.05°. ... Refinements of the structure parameters were made using the GSAS program."
Cautions: Evaluated Data
Critical Temperature for Hg:1223; [Hg(Tl)-Ba-Ca-Cu-O]
| x of Tlx (formula units) |
Specimen Condition () |
Critical Temperature (K) |
| 0 |
As-sintere |
124 |
| 0 |
Annealed |
135 |
| 0.2 |
As-sintere |
133 |
| 0.2 |
Annealed |
138 |
Measurement Method: Four-probe method
"Resistances of samples were measured by the standard four-probe technique with an AC frequency of 27 Hz." No additional measurement details were noted.
Cautions: Unevaluated Data
