Material Specification for Y:124; [Y-Ba-Cu-O]
Process: Solid State Reaction
Notes: "Powders... were prepared by thermal decomposition of a tartaric acid gel with the stoichiometric composition Y:Ba:Cu=1:2:4. The gels were fabricated by dissolving stoichiometric amounts of Y(NO3)3•6H2O (Alfa), Ba(CH3COO)2 (Merck) and Cu(CH3COO)2•H2O (Merck) corresponding to 0.133 moles of Y per liter. Subsequently, 66 mL glacial acetic acid and 0.125 mol tartaric acid were added per liter. The pH was adjusted to 6.2 by adding concentrated aqueous NH3 until an intense blue solution was obtained... After removal of 80% of the water by distillation, the solution started to gelate. During the drying process, the gel blew up to form a fine dry foam which was easily broken into a very fine light blue powder. The decomposition of the dried gel and the formation of the Y-124 phase was monitored by thermogravimetry (TG) and differential thermal analysis (DTA) which was carried out in oxygen, synthetic air (20 vol.% O2 in N2) or argon; the flow rate was in each case 4 L/h. The powders obtained in this way were calcined for about 60 h in flowing oxygen at temperatures Tc between 700 °C and 865 °C... The calcined powders were pressed into pellets at a pressure of about 700 MPa without any intermediate grinding. The pellets were sintered for about 30 h within the same temperature regime, 700 °C to 865 °C... All the calcination and sintering processes were performed under flowing oxygen."
Formula: YBa2Cu4O8
Informal Name: Y:124
Chemical Family: Y-Ba-Cu-O
Chemical Class: Oxide
Structure Type: Polycrystalline
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:
Crystallography for Y:124; [Y-Ba-Cu-O]
| Crystal System: | Orthorhombic |
| Formula Units per Cell: | |
| Space Group: |
|
Cell Parameters
| Calcining Temperature (K) |
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| 710 |
296 |
3.846 |
3.864 |
27.189 |
| 715 |
296 |
3.849 |
3.865 |
27.217 |
| 770 |
296 |
3.841 |
3.866 |
27.212 |
| 800 |
296 |
3.842 |
3.868 |
27.211 |
| 810 |
296 |
3.841 |
3.865 |
27.212 |
| 814 |
296 |
3.842 |
3.865 |
27.238 |
| 820 |
296 |
3.845 |
3.867 |
27.185 |
| 835 |
296 |
3.813 |
3.860 |
27.211 |
| 855 |
296 |
3.841 |
3.871 |
27.253 |
| 865 |
296 |
3.839 |
3.855 |
27.194 |
Measurement Method: X-ray diffration
"The X-ray powder diffraction (XRD) analysis was carried out at room temperature using CuKα radiation. The instrument was calibrated with silicon powder. The lattice parameters were calculated using a least square refinement."
Cautions: Evaluated Data
Critical Temperature for Y:124; [Y-Ba-Cu-O]
| Calcining Temperature (°C) |
Tc(onset) (K) |
Critical Temperature (K) |
| 710 |
83 |
47 |
| 715 |
82 |
48 |
| 770 |
84 |
69 |
| 800 |
83 |
61 |
| 810 |
82 |
71 |
| 814 |
82 |
72 |
| 820 |
92 |
75 |
| 835 |
93 |
76 |
| 855 |
93 |
77 |
| 865 |
93 |
79 |
Measurement Method: Four-probe method
"The temperature dependence of the electrical resistance down to 30 K was measured by employing a standard DC four-probe technique. The currents used in the measurements were around 1 mA to 13 mA." No additional measurement details were noted.
Cautions: Evaluated Data
