Material Specification for Y:124; [Y-Ba-Cu-O]
Process: Solid State Reaction
Notes: "The polycrystalline sample... was prepared using an initial solid state reaction method and a final hot isostatic pressing (HIP) technique. Powders of Y2O3, BaCO3 and CuO were mixed and calcined at 900 °C for 24 h in flowing O2. The sample was then pulverized and the above process repeated twice more. Then, the sample was again pulverized, pressed at 100 MPa, and sintered at 800 °C in flowing O2. The oxygen-HIP treatment was performed at 1050 °C at an oxygen partial pressure of 20 MPa (Ar partial pressure of 80 MPa) for 6 h."
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
|
Temp
K
|
a
Å
|
b
Å
|
c
Å
|
| 296 |
3.843 |
3.873 |
27.254 |
Measurement Method: X-ray powder diffraction
Cautions: Evaluated Data
No measurement details were noted.
Critical Temperature for Y:124; [Y-Ba-Cu-O]
| ΔTc (K) |
Critical Temperature (K) |
| 2.9 ± 0.3 |
80.1 ± 0.2 |
Measurement Method: Adiabatic calorimeter
"The specific heat measurements were performed in an adiabatic calorimeter... Pumped liquid nitrogen was used as the refrigerant. The calorimeter consists of a Cu sample holder filled with the sample and (8 kPa = 60 Torr) of He gas at 300 K and instrumented with a heater, measuring thermometer, and a thermocouple connected to the inner shield. Both this inner and an outer shield were temperature regulated to maintain adiabatic conditions at the sample. Measurement step sizes were about 0.2 to 0.3 K, and a typical run took 3 to 6 days depending on the temperature range covered. The approximately 19 g... sample... was coarsely crushed to ≤1 mm to improve filling of the sample holder and thermal equilibration... with the reproducibility being 0.1% to 0.2%."
Cautions: Evaluated Data
T
c was estimated from the midpoint of the specific heat transition.
Specific Heat for Y:124; [Y-Ba-Cu-O]
| Temperature (K) |
Specific Heat (J kg-1 K-1) |
| 77 |
10.2 |
| 89 |
12.5 |
| 102 |
14.0 |
| 115 |
15.9 |
| 135 |
18.2 |
| 148 |
19.3 |
| 158 |
20.0 |
| 173 |
21.5 |
| 191 |
23.0 |
| 206 |
23.8 |
| 224 |
24.9 |
| 244 |
26.0 |
| 262 |
26.3 |
| 279 |
27.0 |
| 299 |
28.1 |
Measurement Method: Adiabatic calorimeter
"The specific heat measurements were performed in an adiabatic calorimeter... Pumped liquid nitrogen was used as the refrigerant. The calorimeter consists of a Cu sample holder filled with the sample and (8 kPa = 60 Torr) of He gas at 300 K and instrumented with a heater, measuring thermometer, and a thermocouple connected to the inner shield. Both this inner and an outer shield were temperature regulated to maintain adiabatic conditions at the sample. Measurement step sizes were about 0.2 to 0.3 K, and a typical run took 3 to 6 days depending on the temperature range covered. The approximately 19 g... sample... was coarsely crushed to ≤1 mm to improve filling of the sample holder and thermal equilibration... with the reproducibility being 0.1% to 0.2%."
Cautions: Evaluated Data
Data were digitized from Figure 4(a) of the paper.
Debye Temperature for Y:124; [Y-Ba-Cu-O]
| Temperature (K) |
Debye Temperature (K) |
| 91 |
451 |
| 101 |
465 |
| 122 |
490 |
| 142 |
503 |
| 160 |
519 |
| 180 |
532 |
| 200 |
541 |
| 223 |
552 |
| 240 |
561 |
| 255 |
565 |
| 263 |
572 |
| 286 |
576 |
| 300 |
573 |
Measurement Method: Debye model
"... the specific heat data above T
c is used to calculate the phonon contribution and to estimate the Debye temperature." "By subtracting the electronic specific heat... from the total measured value of the specific heat, an estimate of the lattice contribution... may be obtained." "For each temperature, a value... is found such that the Debye specific heat function... is equal to the measured (phonon contribution)."
Cautions: Evaluated Data
Data were digitized from Figure 4(b) of the paper.
