The characteristics of orthorhombicity of YBa 2Cu 3O 7− δ in superconducting state
The temperature dependence of the lattice constants a, b and c of YBa 2Cu 3O 7−δ (δ=0.5) has been determined in a range 28–300 K by high-angle double-crystal X-ray diffractometry, and examined near the superconducting transition temperature T c=55 K. The angle φ that is related to the orthorhombicit...
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Published in | Physica. C, Superconductivity Vol. 377; no. 1; pp. 49 - 55 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
2002
|
Subjects | |
Online Access | Get full text |
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Summary: | The temperature dependence of the lattice constants
a,
b and
c of YBa
2Cu
3O
7−δ
(δ=0.5)
has been determined in a range 28–300 K by high-angle double-crystal X-ray diffractometry, and examined near the superconducting transition temperature
T
c=55 K. The angle
φ that is related to the orthorhombicity of the crystal as
φ=tan
−1(
a/
b) decreases with decreasing temperature; it is found, however, that at
T
c the decrease starts to slow down. The difference between
φ observed and that extrapolated from the normal state is proportional to (1−
T/
T
c)
ξ
. This is new behaviour in connection with the onset of superconductivity, and is discussed in terms of a change in the bond strength around Cu atoms. By comparing the results with that of a specimen with
δ∼0.2
(T
c
∼90
K)
in literature, it is shown that, owing to weaker bond strength around Cu atoms, the crystal with
δ=0.5 exhibits the behaviour more clearly. |
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ISSN: | 0921-4534 1873-2143 |
DOI: | 10.1016/S0921-4534(01)01109-1 |