Formation and decomposition of LaBa2Cu3O7-δ

J. M S Skakle, A. R. West

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The formation and decomposition of LaBa2Cu3O7-δ has been studied by X-ray diffraction and thermogravimetric analysis. The attempted preparation of LaBa2Cu3O7-δ in air or oxygen gives a mixture of a solid solution of composition La1+xBa2-xCu3O7-δ (x≈0.2), and BaCuO2 (J. M. S. Skakle and A. R. West, Physica C, 1994, 220,187). However, heating this mixture in a less oxidising atmosphere such as flowing argon at temperatures above 850 °C for a short time, ca. 16 h, yields a single-phase tetragonal product, which, when annealed in oxygen at lower temperature, gives an orthorhombic superconductor with Tc (onset) ≈ 94 K. The orthorhombic and tetragonal structures have been confirmed by Rietveld refinement of X-ray powder diffraction data; an orthorhombic-tetragonal transition occurs at δ = 0.2. The stability of the single-phase material under air and oxygen has been studied by thermogravimetry. It is stable up to 800 °C in air; at higher temperatures, decomposition to La1+xBa2-xCu3O7-δ (x≈0.2), and BaCuO2 occurs. On prolonged heating of single-phase tetragonal LaBa2Cu3O7-δ at high temperatures, e.g. 875 °C for 64 h under argon, decomposition to give La4-2xBa2+2xCu2-xO10-2* (x≈0.2), BaCuO2 and BaCu2O2 occurs. This is similar to the behaviour of YBCO under low oxygen pressure. Thus, under all conditions studied so far, LaBa2Cu3O7-δ may be considered to be a nonequilibrium phase. In orthorhombic samples of LaBa2Cu3O7-δ prepared by quenching, Tc varies linearly with δ; samples cooled slowly show evidence of a plateau at ca. 94 K for δ≈ - 0.05 to - 0.15.

Original languageEnglish
Pages (from-to)1745-1748
Number of pages4
JournalJournal of Materials Chemistry
Volume4
Issue number11
DOIs
Publication statusPublished - 31 Jan 1994

Fingerprint

Oxygen
Decomposition
decomposition
Argon
oxygen
Thermogravimetric analysis
air
Air
argon
Heating
Temperature
Rietveld refinement
heating
thermogravimetry
diffraction
X ray powder diffraction
X ray diffraction analysis
Superconducting materials
Quenching
Solid solutions

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry

Cite this

Formation and decomposition of LaBa2Cu3O7-δ. / Skakle, J. M S; West, A. R.

In: Journal of Materials Chemistry, Vol. 4, No. 11, 31.01.1994, p. 1745-1748.

Research output: Contribution to journalArticle

Skakle, J. M S ; West, A. R. / Formation and decomposition of LaBa2Cu3O7-δ. In: Journal of Materials Chemistry. 1994 ; Vol. 4, No. 11. pp. 1745-1748.
@article{c4fc8e676b8c4a50ae1fbce8c0d6b6bf,
title = "Formation and decomposition of LaBa2Cu3O7-δ",
abstract = "The formation and decomposition of LaBa2Cu3O7-δ has been studied by X-ray diffraction and thermogravimetric analysis. The attempted preparation of LaBa2Cu3O7-δ in air or oxygen gives a mixture of a solid solution of composition La1+xBa2-xCu3O7-δ (x≈0.2), and BaCuO2 (J. M. S. Skakle and A. R. West, Physica C, 1994, 220,187). However, heating this mixture in a less oxidising atmosphere such as flowing argon at temperatures above 850 °C for a short time, ca. 16 h, yields a single-phase tetragonal product, which, when annealed in oxygen at lower temperature, gives an orthorhombic superconductor with Tc (onset) ≈ 94 K. The orthorhombic and tetragonal structures have been confirmed by Rietveld refinement of X-ray powder diffraction data; an orthorhombic-tetragonal transition occurs at δ = 0.2. The stability of the single-phase material under air and oxygen has been studied by thermogravimetry. It is stable up to 800 °C in air; at higher temperatures, decomposition to La1+xBa2-xCu3O7-δ (x≈0.2), and BaCuO2 occurs. On prolonged heating of single-phase tetragonal LaBa2Cu3O7-δ at high temperatures, e.g. 875 °C for 64 h under argon, decomposition to give La4-2xBa2+2xCu2-xO10-2* (x≈0.2), BaCuO2 and BaCu2O2 occurs. This is similar to the behaviour of YBCO under low oxygen pressure. Thus, under all conditions studied so far, LaBa2Cu3O7-δ may be considered to be a nonequilibrium phase. In orthorhombic samples of LaBa2Cu3O7-δ prepared by quenching, Tc varies linearly with δ; samples cooled slowly show evidence of a plateau at ca. 94 K for δ≈ - 0.05 to - 0.15.",
author = "Skakle, {J. M S} and West, {A. R.}",
year = "1994",
month = "1",
day = "31",
doi = "10.1039/JM9940401745",
language = "English",
volume = "4",
pages = "1745--1748",
journal = "Journal of Materials Chemistry",
issn = "0959-9428",
publisher = "Royal Society of Chemistry",
number = "11",

}

TY - JOUR

T1 - Formation and decomposition of LaBa2Cu3O7-δ

AU - Skakle, J. M S

AU - West, A. R.

PY - 1994/1/31

Y1 - 1994/1/31

N2 - The formation and decomposition of LaBa2Cu3O7-δ has been studied by X-ray diffraction and thermogravimetric analysis. The attempted preparation of LaBa2Cu3O7-δ in air or oxygen gives a mixture of a solid solution of composition La1+xBa2-xCu3O7-δ (x≈0.2), and BaCuO2 (J. M. S. Skakle and A. R. West, Physica C, 1994, 220,187). However, heating this mixture in a less oxidising atmosphere such as flowing argon at temperatures above 850 °C for a short time, ca. 16 h, yields a single-phase tetragonal product, which, when annealed in oxygen at lower temperature, gives an orthorhombic superconductor with Tc (onset) ≈ 94 K. The orthorhombic and tetragonal structures have been confirmed by Rietveld refinement of X-ray powder diffraction data; an orthorhombic-tetragonal transition occurs at δ = 0.2. The stability of the single-phase material under air and oxygen has been studied by thermogravimetry. It is stable up to 800 °C in air; at higher temperatures, decomposition to La1+xBa2-xCu3O7-δ (x≈0.2), and BaCuO2 occurs. On prolonged heating of single-phase tetragonal LaBa2Cu3O7-δ at high temperatures, e.g. 875 °C for 64 h under argon, decomposition to give La4-2xBa2+2xCu2-xO10-2* (x≈0.2), BaCuO2 and BaCu2O2 occurs. This is similar to the behaviour of YBCO under low oxygen pressure. Thus, under all conditions studied so far, LaBa2Cu3O7-δ may be considered to be a nonequilibrium phase. In orthorhombic samples of LaBa2Cu3O7-δ prepared by quenching, Tc varies linearly with δ; samples cooled slowly show evidence of a plateau at ca. 94 K for δ≈ - 0.05 to - 0.15.

AB - The formation and decomposition of LaBa2Cu3O7-δ has been studied by X-ray diffraction and thermogravimetric analysis. The attempted preparation of LaBa2Cu3O7-δ in air or oxygen gives a mixture of a solid solution of composition La1+xBa2-xCu3O7-δ (x≈0.2), and BaCuO2 (J. M. S. Skakle and A. R. West, Physica C, 1994, 220,187). However, heating this mixture in a less oxidising atmosphere such as flowing argon at temperatures above 850 °C for a short time, ca. 16 h, yields a single-phase tetragonal product, which, when annealed in oxygen at lower temperature, gives an orthorhombic superconductor with Tc (onset) ≈ 94 K. The orthorhombic and tetragonal structures have been confirmed by Rietveld refinement of X-ray powder diffraction data; an orthorhombic-tetragonal transition occurs at δ = 0.2. The stability of the single-phase material under air and oxygen has been studied by thermogravimetry. It is stable up to 800 °C in air; at higher temperatures, decomposition to La1+xBa2-xCu3O7-δ (x≈0.2), and BaCuO2 occurs. On prolonged heating of single-phase tetragonal LaBa2Cu3O7-δ at high temperatures, e.g. 875 °C for 64 h under argon, decomposition to give La4-2xBa2+2xCu2-xO10-2* (x≈0.2), BaCuO2 and BaCu2O2 occurs. This is similar to the behaviour of YBCO under low oxygen pressure. Thus, under all conditions studied so far, LaBa2Cu3O7-δ may be considered to be a nonequilibrium phase. In orthorhombic samples of LaBa2Cu3O7-δ prepared by quenching, Tc varies linearly with δ; samples cooled slowly show evidence of a plateau at ca. 94 K for δ≈ - 0.05 to - 0.15.

UR - http://www.scopus.com/inward/record.url?scp=0004421889&partnerID=8YFLogxK

U2 - 10.1039/JM9940401745

DO - 10.1039/JM9940401745

M3 - Article

AN - SCOPUS:0004421889

VL - 4

SP - 1745

EP - 1748

JO - Journal of Materials Chemistry

JF - Journal of Materials Chemistry

SN - 0959-9428

IS - 11

ER -