Material Specification for Y:124; [Y-Ba-Cu-O]
Process: Solid State Reaction
Notes: "... the 1:2:4 compound was prepared by combining stoichiometric weights of Y2O3 (Johnson Matthey, Reaction 99.9999%), CuO (Johnson Matthey, puratronic 99.999%), and anhydrous BaO2 which was prepared from BaCO3 (Johnson Matthey, puratronic 99.997%). A three step procedure was used which utilized an externally heated oxygen pressure vessel... In the first step, the starting materials were converted to 1:2:4 by heating at 960 °C in (5.57 MPa = 55 atm) O2 for 24 h... In the second step, cold pressed pellets were densified by hot isostatic pressing in gold capsules at 875 °C under a pressure of (0.2 GPa = 2 kbar)... A third step which consists of anneals at two different temperatures was needed to produce optimum properties. In this step the sample was exposed to high pressure oxygen, first at 1010 °C, (4.25 MPa = 42 atm) for 2 h followed by an anneal at 950 °C, (5.57 MPa = 55 atm) for 24 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
|
| 295 |
3.8413(6) |
3.8711(6) |
27.239(4) |
| 373 |
3.8463 |
3.8762 |
27.285 |
| 473 |
3.8507 |
3.8769 |
27.350 |
| 573 |
3.8545 |
3.8822 |
27.375 |
| 673 |
3.8599 |
3.8854 |
27.436 |
| 773 |
3.8627 |
3.8883 |
27.452 |
| 873 |
3.8687 |
3.8957 |
27.528 |
| 973 |
3.8773 |
3.9048 |
27.605 |
| 1073 |
3.8848 |
3.9133 |
27.655 |
Measurement Method: X-ray diffraction
"For room temperature measurements the 1:2:4 sintered product was ground in a glove box containing argon and suspended in a mixture of toluene/vaselin to protect the powder from moisture. Silicon and fluorophlogopite were mixed with the powder and used as internal standards... A thin layer of the mixture was spread on an off-cut quartz plate and mounted on a Scintag 2θ/θ goniometer. Digitized data were collected from 4 to 94° 2θ scanning at 0.1°/min with steps of 0.01° 2θ and Cu Kα radiation."
"For high temperature lattice parameter measurements, the phase pure 1:2:4 samples were ground in a glove box and mixed with a Pt internal standard (Alfa Chemicals, 99.999%). The powder mixture was mounted on a platinum strip heater of a Buehler high temperature XRD furnace attached to a Scintag 2θ/θ goniometer... We estimate that thermal gradients limit the accuracy of temperature to within ± 5 °C. Diffraction data were collected from 4 to 94° 2θ using Cu Kα radiation. The scans were done at a ratae of 0.25°/min with 0.01° steps at temperatures from 22 °C to 750 °C under flowing O
2 gas at (0.1 MPa = 1 atm)."
"The axial coefficients of thermal expansion from 22 °C to 750 °C (were derived from the x-ray lattice parameters) along a, b and c..."
Cautions: Evaluated Data
Thermal Expansion for Y:124; [Y-Ba-Cu-O]
| Axis () |
Temperature Range (°C) |
Thermal Expansion (10-6 K-1) |
| a |
22 - 750 |
15.6 |
| b |
22 - 750 |
15.0 |
| c |
22 - 750 |
21.0 |
Measurement Method: X-ray diffraction
"For room temperature measurements the 1:2:4 sintered product was ground in a glove box containing argon and suspended in a mixture of toluene/vaselin to protect the powder from moisture. Silicon and fluorophlogopite were mixed with the powder and used as internal standards... A thin layer of the mixture was spread on an off-cut quartz plate and mounted on a Scintag 2θ/θ goniometer. Digitized data were collected from 4 to 94° 2θ scanning at 0.1°/min with steps of 0.01° 2θ and Cu Kα radiation."
"For high temperature lattice parameter measurements, the phase pure 1:2:4 samples were ground in a glove box and mixed with a Pt internal standard (Alfa Chemicals, 99.999%). The powder mixture was mounted on a platinum strip heater of a Buehler high temperature XRD furnace attached to a Scintag 2θ/θ goniometer... We estimate that thermal gradients limit the accuracy of temperature to within ± 5 °C. Diffraction data were collected from 4 to 94° 2θ using Cu Kα radiation. The scans were done at a ratae of 0.25°/min with 0.01° steps at temperatures from 22 °C to 750 °C under flowing O
2 gas at (0.1 MPa = 1 atm)."
"The axial coefficients of thermal expansion from 22 °C to 750 °C (were derived from the x-ray lattice parameters) along a, b and c..."
Cautions: Evaluated Data
