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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: Cation Stoichiometric La2CaCu2O6+y: An Undoped Oxide Superconducting at 45 K
Author(s): A.Fuertes, X.Obradors, J.M.Navarro, P.Gomez-Romero, N.Casan-Pastor, F.Perez, J.Fontcuberta, C.Miravitlles, et al
Publication: Ceramic Transactions Volume: 18 Issue: Not Available Year: 1991 Page(s): 126-136
Editor(s): Not Available
Publisher: American Ceramic Society
Language: English
Notes: et al. = J.Rodriguez-Carvajal, and B.Martinez
Keywords: Material Specification, Crystallography, Critical Temperature, Magnetic Susceptibility

Materials and Properties

La:22; [La(Ca)-Cu-O]
Material Specification for La:22; [La(Ca)-Cu-O] Process: Solid State Reaction
Notes: "La2CaCu2O6+x was prepared using an oxide precursor route... In a first step, pure La2CuO4 was obtained by heating in air at 1080 °C a 1:1 mixture of La2O3 and CuO (99.99% Aldrich) with an intermediate regrinding. Then, a 1:1:1 molar ratio of La2CuO4, CaCO3 (Baker 99.995%) and CuO were subject to a treatment involving heating in air at 900 °C during 12 h and further reheating at 1050 °C with several intermediate regrindings. Finally, the sample was furnace-cooled to room temperature. Portions of sample were subject to annealing in O2 (P = 0.1 MPa = 1 atm) during 48 h at 900 °C and in Ar (P = 0.1 MPa = 1 atm) during 6 h at 900 °C."
Formula: La2CaCu2O6+x
Informal Name: La:22
Chemical Family: La(Ca)-Cu-O
Chemical Class: Oxide
Structure Type: Polycrystalline
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:

Crystallography for La:22; [La(Ca)-Cu-O]
Crystal System: Tetragonal
Formula Units per Cell:
Space Group: I4/mmm
Cell Parameters
Occupancy () Temp K a Å b Å c Å
-- 1.5 3.82820(5) -- 19.4498(4)
Atomic Coordinates
Occupancy () Atom Temp K a-axis b-axis c-axis
0.77(2) Ca(1) 1.5 0.0000 0.0000 0.0000
0.23(2) La(1) 1.5 0.0000 0.0000 0.0000
1.77(4) La(2) 1.5 0.0000 0.0000 0.1756(1)
0.23(4) Ca(2) 1.5 0.0000 0.0000 0.1756(1)
2.0 Cu 1.5 0.0000 0.0000 0.5853(1)
4.0 O(1) 1.5 0.0000 0.5000 0.0821(1)
2.0 O(2) 1.5 0.0000 0.0000 0.7040(1)
0.037(8) O(3) 1.5 0.0000 0.0000 0.5000
Measurement Method: Neutron diffraction
"Neutron powder diffraction measurements were performed... with the high resolution diffractometer D2B at the Institut Laue-Langevin in Grenoble. Neutrons of wavelength 1.5945 σ were selected for the experiments. The analysis of the data was performed using the programs FULLPROF and SHELX-76."

Cautions: Evaluated Data
Critical Temperature for La:22; [La(Ca)-Cu-O]
Critical Temperature (K)
45
Measurement Method: Ac susceptibility
"A.C. magnetic susceptibility measurements were performed on powdered samples using a Lake Shore instrument. The experiments were carried out at a fixed frequency (111.1 Hz) and the a.c. ripple field was h = (79.6 A/m = 1 Oe)."

Cautions: Evaluated Data
Magnetic Susceptibility for La:22; [La(Ca)-Cu-O]
Sample Condition () Temperature (K) Magnetic Susceptibility (arbitrary)
annealed 4 -0.0044
annealed 9 -0.0040
annealed 12 -0.0032
annealed 16 -0.0017
annealed 19 -0.0010
annealed 22 -0.0003
annealed 31 -0.0003
annealed 37 -0.0002
annealed 46 0.0004
annealed 55 0.0005
annealed 63 0.0006
as made 4 -0.0050
as made 10 -0.0046
as made 14 -0.0034
as made 19 -0.0018
as made 22 -0.0008
as made 28 -0.0005
as made 38 -0.0002
as made 46 -0.0001
as made 55 0.0005
as made 62 0.0005
Measurement Method: Ac susceptibility
"A.C. magnetic susceptibility measurements were performed on powdered samples using a Lake Shore instrument. The experiments were carried out at a fixed frequency (111.1 Hz) and the a.c. ripple field was h = (79.6 A/m = 1 Oe)."

Cautions: Evaluated Data
Digitized data were obtained from Figure 3 of the paper.