Material Specification for Hg:1212; [Hg-Ba-Ca-Cu-O]
Process: Solid State Reaction
Notes: "Powder samples... were obtained by high-pressure and high-temperature reactions using the belt-type apparatus of the Laboratoire de Cristallographie. First, the precursor with the nominal composition Ba2CaCu2Ox was prepared from a well-ground stoichiometric mixture of BaO2 (95% purity, Aldrich), CaCO3 (99% purity, Merck) and CuO (NormaPur, Prolabo) by annealing at 800 °C in air for 12 h. Then, the stoichiometric amount of yellow HgO (98% purity, Aldrich) was added and the mixtures were thoroughly ground in an agate mortar and sealed in a Pt capsule specific for high-pressure synthesis. Various experimental conditions were tried in order to obtain the Ca-based Hg-1212 as a pure sample. In these experiments the pressure was first increased to the nominal value; subsequently, the temperature was raised to the desired value during one hour. Then the pressure and the temperature were kept constant for one hour, after which the furnace power supply was shut off and the pressure was decreased to normal conditions in one hour."
Formula: HgBa2CaCu2O6+x
Informal Name: Hg:1212
Chemical Family: Hg-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:1212; [Hg-Ba-Ca-Cu-O]
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| Crystal System: | Tetragonal |
| Formula Units per Cell: | 1 |
| Space Group: |
P4/mmm
|
Cell Parameters
| Occupancy () |
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| -- |
296 |
3.85766(4) |
-- |
12.6562(3) |
Atomic Coordinates
| Occupancy () |
Atom |
Temp
K
|
a-axis |
b-axis |
c-axis |
| 1.00 |
Hg |
296 |
0 |
0 |
0 |
| 1.00 |
Ba |
296 |
0.5 |
0.5 |
0.2197(2) |
| 1.00 |
Ca |
296 |
0.5 |
0.5 |
0.5 |
| 1.00 |
Cu |
296 |
0 |
0 |
0.3754(5) |
| 1.00 |
O(1) |
296 |
0 |
0 |
0.159(2) |
| 1.00 |
O(2) |
296 |
0.5 |
0 |
0.389(2) |
| 0.26(5) |
O(3) |
296 |
0.5 |
0.5 |
0 |
Measurement Method: X-ray diffraction
"The formation of the new phase... was revealed by X-ray powder analysis, performed with a Guinier FR-552 focusing camera and CuKα
1 radiation (1.54056 σ). Finely powdered germanium (a=5.6574 σ) was used as internal standard."
Cautions: Evaluated Data
Magnetic Susceptibility for Hg:1212; [Hg-Ba-Ca-Cu-O]
| Temperature (K) |
Magnetic Susceptibility (arbitrary) |
| 58 |
-5.18 |
| 83 |
-3.73 |
| 92 |
-1.22 |
| 95 |
-0.69 |
| 103 |
-0.61 |
| 123 |
-0.53 |
| 131 |
-0.08 |
| 140 |
-0.08 |
Measurement Method: Ac susceptibility
"Magnetic susceptibility measurements were carried out in the 12-160 K temperature range with an external field of (796 A/m = 10 Oe) and a frequency of 27 Hz. The temperature was measured by a calibrated silicon diode with an accuracy 1 K."
Cautions: Evaluated Data
"Actually, two onsets at two different temperatures are visible, one at 129 K and one at 94 K."
Digitized data were obtained from Figure 1 of the paper.
