NIST High Temp. Superconducting Materials (HTS) Database

NIST High Temp. Superconducting Materials (HTS) Database:

NIST Standard Reference Database 62

Last Update to Data Content: 1996

DOI: https://doi.org/10.18434/T4KP8J

Bibliographic Information

Title: Variation of the Superconducting and Structural Properties of Y₂Ba₄Cu₇O_z with Oxygen Content (14.1 T_c≤ 95 K)
Author(s): J.Y. Genoud, T. Graf, G. Triscone, A. Junod, and J. Muller
Publication: Physica C Volume: 192 Issue: Not Available Year: 1992 Page(s): 137-146
Editor(s): Not Available
Publisher: Elsevier Science Publishers B.V.
Language: English
Notes: Not Available
Keywords: Material Specification, Crystallography, Critical Temperature

Materials and Properties

Y:247; [Y-Ba-Cu-O]

Material Specification for Y:247; [Y-Ba-Cu-O] Process: Solid State Reaction
Notes: "High-purity (5N) Y₂O₃, BaCO₃ and CuO powders mixed in the stoichiometric ratio Y:Ba:Cu=2:4:7 and fired in flowing oxygen at ambient pressure between 880 and 920 °C for one week and then reground. This procedure was applied twice. The prereacted powders were cold pressed into pellets of about 0.4 g and 6 mm in diameter. The 247 phase is then obtained by two successive heatings during 1 day at 990 °C and (2.0 MPa = 20 bar) O₂. To vary and to homogenize the oxygen content, the samples were annealed under controlled oxygen atmosphere. The high temperature state is then quenched by dropping the sample into liquid gallium. The high oxygen concentrations are obtained in an induction furnace... which can sustain a pressure of (10 MPa = 100 bar) O₂. The quenching occurs by convection at a rate of 500 °C/min when the RF power is turned off."
Formula: Y₂Ba₄Cu₇O_x
Informal Name: Y:247
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:247; [Y-Ba-Cu-O]

Crystal System:	Orthorhombic
Formula Units per Cell:
Space Group:

**Cell Parameters**
x of O_x (formula units)	Temp K	a Å	b Å	c Å
14.1	296	3.8462	3.8664	50.8475
14.3	296	3.8470	3.8682	50.7884
14.6	296	3.8406	3.8753	50.6974
14.8	296	3.8360	3.8761	50.6980
15.0	296	3.8306	3.8779	50.6096
15.3	296	3.8313	3.8778	50.6018

Measurement Method: X-ray diffraction
"The crystal structure was studied at ambient temperature by X-ray diffraction using a Guinier camera with CuKα radiation. Silicon was added to the powdered samples as an internal standard (a=5.4308 σ). The lattice parameters were determined from least-squares fit to about 30 lines."

Cautions: Evaluated Data
Digitized data were obtained from Figure 9 of the paper.

Critical Temperature for Y:247; [Y-Ba-Cu-O]

x of O_x (formula units)	Critical Temperature (K)
15.32	92.3
15.15	92.9
15.09	93.1
15.09	86.7
15.05	83.9
15.04	83.5
15.03	89.8
15.02	76.8
14.94	83.4
14.89	78.1
14.85	71.9
14.82	68.2
14.78	71.5
14.78	69.6
14.71	64.6
14.64	57.3
14.59	55.1
14.55	48.3
14.53	46.0
14.48	52.9
14.43	44.1
14.41	41.0
14.39	39.5
14.39	36.0
14.35	36.2
14.35	33.7
14.22	35.1
14.13	32.3

Measurement Method: Mutual inductance bridge
"The AC diamagnetism... was recorded in a mutual inductance bridge working at 73 Hz in a magnetic field of (7.96 A/m = 0.1 Oe) RMS."

Cautions: Evaluated Data
The authors varied the oxygen content by varying the annealing conditions by using different annealing temperatures, annealing times, and partial oxygen pressures.