Poole Ch.P., Jr. Handbook of Superconductivity
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336
Chapter 8: Crystal Structures of High-T~ Superconducting Cuprates
Fig. 8.25.
o
o
o
9.32
L '
i
'
i '
9.28
9.24 ~0
9.20
-
- i...
9.16 - O ~ C
-
o~
9.12 -
[ i I '
9
[Man89]
0 [Man94]
o
""qL.. -
9.08 -
9.04
9.00 -
3.84~ .....
3.82 I i 1 , I
0.5 0.6 0.7
a
9 w-
l I I
0.8 0.9 1.0
x in T1Ba2.xLaCuO5
Cell parameters vs La content for T1Ba2_xLaxCuO5 (Manako
et al.,
1989; Manako and Kubo,
1994).
Fig. 8.26.
50
40
30
E,~ ~ 20
10
O@
0.5
1 ' I ' I ' I '
o
%
0.6 0.7 0.8 0.9 1.0
x in T1Ba2.xLaCuO 5
Superconducting transition temperature vs La content for T1Ba2_xLaxCuO5 (Manako
et al.,
1989; Manako and Kubo, 1994).
H. Crystallographic Data Sets 337
T1Sr2CuOs_ 6, is reported to be either tetragonal (Kim
et al.,
1989) or orthor-
hombic
(Pmmm)
(Ganguli and Subramanian, 1991), depending on the oxygen
content. The latter compound can be stabilized by partial substitution of T1 by Pb
and becomes superconducting when Sr is partly replaced by La or a rare-earth
element (Subramanian, 1990). Upon substituting T1 by Pb, the oxygen content of
oxygen-deficient
(Tll_xPbx)Sr2Cu05_ 6
is increased and the compound undergoes
a structural transformation from the orthorhombic to the tetragonal modification
at x- 0.12 (Kaneko
et al.,
1991). Ohshima
et al.
(1993) found the cell to be
orthorhombic for 6- 0.69, but tetragonal for 6 _< 0.42 (x- 0.5). A super-
structure with doubling of the b-parameter and an ordered arrangement of
oxygen vacancies in the CuO2 layer was reported for T1Sr2CuO4.515 (Ohshima
et al.,
1994).
A superconducting (Pb,Cu)-1201 compound, with nominal composition
Pbo.6SrLaCul.5Oy (T c -- 28 K), was first reported by Adachi
et al.
(1990b). Two
partly occupied cation sites in the
additional
layer were considered in the
structural refinement on Pb0.sSrLaCul.5Os+ 6
((Pbo.sCuo.5)(Sro.sLao.5)2Cu05+6,
Pb in l(a) 0 0 0 and Cu in 4(l) 0.104 0 0, occupancy 0.5 and 0.125) (Khasanova
et al.,
1996a). In addition, distinct sites were refined for La and Sr, and the O site
in the
bridging
layers was split.
The Ga-1201 compounds known so far are not superconducting and
contain a mixture of Sr and La (or rare-earth elements) in the
bridging
layers.
Their structures are orthorhombic because of the arrangement of the GaO4
tetrahedra in chains.
HgBa2CuO4.1o, with T c -94 K, crystallizes in the tetragonal space group
P4/mmm
(Putilin
et al.,
1993a). In Wagner
et al.
(1993) partial substitution of rig
by Cu (7 at.%) was proposed to be accompanied by the presence of extra O sites
(4(i) 0 1 0.043 and l(c) 89 1 0, occupancy 0.09 and 0.059). According to
Alexandre
et al.
(1995), the Cu content on the Hg site cannot exceed 10 at.%.
Like many other high-T c superconducting cuprates, HgBa2CuO4+ 6 can be over-
doped, the compound becoming nonsuperconducting for 6- 0.23 (Loureiro
et
al.,
1995).
The crystal structure of CSr2CuO5 was first refined in space group
P4/mmm
(Babu
et al.,
1991). Miyazaki
et al.
(1992a) used an 8-fold supercell
to account for an ordered arrangement of mutually perpendicular CO3 triangular
groups. Partial substitution of Sr by Ba (25 at.%) was first reported by Armstrong
and Edwards (1992), who refined the average structure. A 2-fold supercell
(P4/mbm, ~/2a, c)
was adopted for the refinement of the structure of
CSrBaCuOs+ 6 by Chaillout
et al.
(1992) and Miyazaki
et al.
(1993). A similar
2-fold supercell, but space group P4212 was proposed for Co.89Ba1.11Sro.89-
Cu1.1104.99 (Izumi
et al.,
1992). Superconductivity (T c -- 26 K) was first reported
for the compound Co.9Bal.lSro.9CUl.lO4.9+6, prepared under 5 MPa 02 (Kinoshita
and Yamada, 1992a).
Carbon-based 1201 compounds with 50% of the carbon atoms substituted
by, for example, T1, Pb, Bi, Hg, Mo, Cr, and/or V crystallize with a 2-fold
338
Chapter 8: Crystal Structures of High-To Superconducting Cuprates
superstructure where the translation period along [0 0 1 ] contains one slab with
carbonate groups and one slab with the mentioned cations in the
additional
layer.
Larger supercells, resulting from a crystallographic shear in the (1 0 0) or
(1 1 0) planes by c/2, are often observed. The cell parameters a and b of such
so-called (1 0 0)- or (1 1 0)-collapsed oxycarbonate structures depend on the
periodicity of the crystallographic shear planes, whereas the c-parameter corre-
sponds to two stacking units (Maignan
et aL,
1995b).
1212
CUlBa2Y1Cu207
AB2CD207,
oP13, (47)
Pmmm-tsrq2hea
-002-oC-DO2-OB-AO'-OB-
BazYCu307, T c -- 91 K, a PN, T -- 300 K, R B = 0.0715
(Capponi
et aL,
1987)
(47)
Pmmm,
a = 3.8206, b = 3.8851, c = 11.6757 A,
Z--1 Fig. 12
Atom WP PS x
Occ.
Cu(1) l(a)
mmm 0
1
Ba 2(t)
mm2
Cu(2) 2(q)
mm2 0
1
Y l(h)
mmm
O(1) l(e)
mmm 0
0(2) 2(q)
mm2 0
0(3) 2(r)
mm2 0
1
0(4) 2(s)
mm2
0
0.1841
0.3549
1
_
2
0
0.1581
0.3777
0.3779
a Value taken from Cava
et al. (1987b).
(continued)
H. Crystallographic Data Sets
339
Compound a (A) b (A) c (A) T c (K) Ref.
BazLaCu2.9407 3.8829 3.9342 11.810 89 1
Ba2PrCu3Oy a 3.88 3.93 11.84 80 2
BazNdCu307 3.8590 3.9112 11.7412 91 b 3
Ba2SmCu307 3.8440 3.9018 11.7248 93.8 c 4
Ba2EuCu307 3.8384 3.8973 11.7069 94.5 c 4
Ba2GdCu307 3.8350 3.8947 11.6992 94.7 c 4
BaSrGdCu306.94 a 3.804 3.863 11.588 82.6 b 5
Ba2DyCu306.9o 3.84215 3.88721 11.67772 92 6, 7
BaSrDyCu306.93 a 3.816 3.838 11.542 83 b 8
Ba2HoCu306.96 3.8205 3.8851 11.6822 93.4 c 9
BaSrHoCu306.94 d 3.789 3.851 11.546 79 b 10
Ba2ErCu307 3.8128 3.8781 11.6644 93.2 c 11
BaSrErCu306.94 d 3.791 3.847 11.560 78 b 10
Ba2TmCu307 3.8087 3.8746 11.6655 90.5 c 12
BaSrTmCu306.94 a 3.821 3.836 11.550 70 b 10
Ba2YbCu307 3.8018 3.8710 11.6576 90.0 c 13
Ba2YCu307 3.8206 3.8851 11.6757 91 14, 15
Ba2YCu2.89Alo.1107
3.851 3.859 11.677 82 e 16
Ba2YCu2.82Zno.1806.9 f 3.835 e 3.880 e 11.67 e 45 e 17
BazYCuz.91Feo.o907_,~ a 3.852 3.861 11.686 85 18
Ba2YCuz.ysNio.2507 3.8191 3.8857 11.6571 63.9 19
BaSrYCu306.94 d 3.791 3.845 11.542 79 b 10
a
Nominal composition.
b From resistivity measurements (zero resistivity).
c From resistivity measurements (midpoint).
d Nominal composition, oxygen content from chemical analysis.
e Value taken from figure.
fNominal composition, oxygen content from TG analysis.
References: 1, Yoshizaki
et al.
(1987); 2, Zou
et al.
(1997); 3, Takita
et al.
(1988); 4, Asano
et al.
(1987c); 5, Wang
et al.
(1995); 6, Currie and Weller (1993); 7, Guillaume
et al.
(1994); 8, Wang
et al.
(1992b); 9, Asano
et al.
(1987b); 10, Wang
et al.
(1992a); 11, Ishigaki
et al.
(1987a); 12, Ishigaki
et
al.
(1987b); 13, Asano
et al.
(1987a); 14, Capponi
et al.
(1987); 15, Cava
et al.
(1987b); 16, Siegrist
et
al.
(1987a); 17, Westerholt
et al.
(1989); 18, Xu
et al.
(1989); 19, Tarascon
et al.
(1987).
340 Chapter
8:
1212
Crystal Structures of High-Tc Superconducting Cuprates
CUlBa2Y1Cu206.26
AB2CD206+a, tP12, (123) P4/mmm-ihg2OC)da
-DO2-.C-DO2-OB-A.
BazYCu306.26, n.s., SN, T = 298 K, R w = 0.047
(Renault
et al., 1987)
(123)
P4/mmm, a = 3.8573, c = 11.7913 A, Z = 1 Fig. 13
Atom WP PS x y
Occ.
Cu(1) l(a)
4/mmm 0
1
Ba 2(h) 4mm
Cu(2) 2(g) 4mm 0
1
Y l(d) 4/mmm
O(1) 2(f) mmm . 0
0(2) 2(g) 4mm 0
0(3) 4(i) 2mm . 0
0
0.1940
0.3598
1
_
2
0
0.1533
0.3793
0.13
Compound a (A) c (A) Tr (K)
Ref.
BaSrLaCu306.94 a 3.877 11.728
Bal.sLal.5Cu307.2o 3.9069 11.6925
Bal.sLaCao.sCu307.Ol 3.8742 11.7138
Bal.25Lal.25Cao.sCu307.137 3.873 11.622
Ba2PrCu2.9o706.16 3.9060 11.824
BaSrPrCu306.94 a 3.859 11.551
Ba2NdCu306.24 3.9015 11.8539
BaSrNdfu306.94 a 3.870 11.622
Bal.75Ndl.25Cu307.16 3.8923 11.7145
Bal.6Ndfao.4Cu306.96 3.8752 11.6963
BaSrSmCu306.94 a 3.851 11.591
Bal.8Sml.2Cu307.2 3.8730 11.6763
57 b
n.s.
78
79.2
n.s.
n.s.
n.s.
74 b
40 ~
65 c
80 b
43 a
(continued)
H. Crystallographic Data Sets 341
BaSrEuCu306.94 a
3.844 11.579 80 b 1
Bal.sEU1.2Cu307.18
e
3.873 11.631 28/9 10
BaSrGdCu307 e 3.835 11.554 86 b 11
Ba2DyCu306.25 3.8675 11.811 n.s. 12
BaSrDyCu3 O6.94 a 3.828 11.533 80 b 13
Ba2HoCu306 3.8650 11.824 n.s. 12
Ba2ErCu306.18 3.8648 11.857 n.s. 14
BazYCu306.26 3.8573 11.7913 n.s. 15
Ba2YCu2.55Zno.4506.9 e 3.850 c 11.67 c n.s. 16
BazYCuz.7Feo.307.15 f 3.8655 11.674 35 r 17
BazYo.73Cao.zyCu2.7oCoo.3oO 7
3.8646 11.7257 84 18
Ba2YCu2.55Nio.4506.9 e 3.865 c 11.63 c 50 a 16
Sr2Yfu3Oy g 3.7949 11.4102 60 19
TaB azLaCu2 O8 3.9674 12.052 n.s. 20
NbBazLaCu208 3.9679 12.001 h n.s. 21
RuSrzSmCu208 3.852 11.56 n.s. 22
a
Nominal composition; oxygen content from chemical analysis.
b From resistivity measurements (zero resistivity).
c Value taken from figure.
d From resistivity measurements (zero resistivity); value taken from figure.
e Nominal composition, oxygen content from TG analysis.
fNominal composition.
g Prepared at 7 GPa; nominal composition.
h Additional reflections indicate superstructure
(P4/mbm
or
P4bm, ~/2a,
c); 4-fold superstructure
(I4/mcm,
a = 5.6107, c = 23.9863 A) in Rey
et al.
(1990).
References: 1, Wang
et al.
(1992a); 2, Izumi
et al.
(1988); 3, Skakle and West (1994); 4, Goldschmidt
et al.
(1993); 5, Lowe-Ma and Vanderah (1992); 6, Shaked
et al.
(1990); 7, Kramer
et al.
(1994); 8,
Skakle and West (1996); 9, Asano
et al.
(1988); 10, Li
et al.
(1988); 11, Wang and B~iuerle (1991); 12,
Onoda
et al.
(1987); 13, Wang
et al.
(1992b); 14, Mirmelstein
et al.
(1992); 15, Renault
et al.
(1987);
16, Westerholt
et al.
(1989); 17, Xu
et al.
(1989); 18, Suard
et al.
(1993); 19, Okai (1990); 20,
Murayama
et al.
(1988); 21, Kopnin
et al.
(1996); 22, Bauernfeind
et al.
(1995).
342 Chapter 8:
1212
Crystal Structures of High-Tc Superconducting Cuprates
TllBa2(Cao.87Tlo. 13)1Cu207
AB2CD207, tP13, (123) P4/mmm-ihg2dca
-DO2-.C-DO2-OB-A O-OB-
Tll.13Ba2Cao.svCu207, T c - 80 K, SX, R w = 0.032
(Kolesnikov
et aL, 1989)
(123)
P4/mmm, a = 3.8472, c = 12.721 A, Z = 1 Fig. 14
Atom WP PS x
z Occ.
T1 4(/)
m2m.
Ba 2(h) 4mm
Cu 2(g) 4mm
Ca a l(d) 4/mmm
O(1) l(c) 4/mmm
0(2) 2(g) 4mm
0(3) 4(i) 2mm.
0.0877
1
2
0
1
2
1
2
0
0
0
0.21550
0.3740
1
_
2
0
0.1582
0.3797
0.25
a
Ca -- Cao.87Tlo.13.
Compound
a (A)
c (A)
T c (K)
Ref.
T11.13Ba2Cao.87Cu207
T1Ba1.7Lao.3CaCu207
a
T1Ba2Cao.8Ndo.2Cu207
T1Ba2Cao.8Yo.zCu207 a
T1BazYCu207
T1BaSrYCu207
T1SrzCaCu207
T11.15
Sr2Cao.gzCu206.85
Tlo.97Cro.1 oSr2Cao.93Cu207
Tlo.sPbo.sSrzCaCu207 a
Tlo.sPbo.5 Sr2Cao.ysYo.zsCu207 a
Tlo.67Bio.33 SrzCaCu207
Tlo.55Bio.45 SrzCaCu207
Tlo.sBio.sSrzCaCu207 a
T1Srl.sLao.sCaCu207 a
T1Srl.65Ceo. 35CaCu207_6 a
3.8472
3.843
3.85638
3.86 b
3.86873
3.8421
3.794
3.79395
3.8155
3.806
3.8196
3.7922
3.7988
3.796
3.800
3.8126
12.721
12.72
12.6534
12.706
12.4732
12.2064
12.133
12.1281
12.0222
12.147
12.136
12.0661
12.076
12.113
12.050
12.0386
80
100
100
100
n.s.
n.s.
2O
6O
100
c
9O
105
86
94.9
90 c
92
62
1
2
3
4
5
6
7
8
9
lO, 11
12
13
14
15
16
17
(continued)
H. Crystallographic Data Sets 343
T1Sr2Cao.5Lao.sCu2Oy a
T1Sr2Pro.6Cao.4Cu207 a
T1Srz.4Ndo.6Cu207
Tlo.97Sr2Luo.60Cao.40Cu206.94
T1SreYCu207
Pbo.5 Sr2.5Cao.5Yo.sCu207
Pbo.5 SrzCaYo.sCu206.78
Pbo.sMgo.sSrzCao.sYo.sCu207_~ a
Pbo.7Sco.3 Sr2Cao.5Yo.5Cu207 a
Pbo.sCdo 5SrzCao.5Yo.5Cu207
Pbo.75Sr2Cao.7Yo.3Cu2.2507_6 a
Pbo.65SrzCao.3Yo.7Cu2.3507.05
Pbo.5 SrzCao.sYo.5Cu2.507_6 a
Bio.33Cdo.67Sr2YCu207 a
Bio.3Sr2YCu2.707.94 d
Ceo.sCdo.sSr2YCu207 a
3.82
3.842
3.79601
3.8157
3.8166
3.8123
3.8249
3 8265
3 8055
3 8159
3 81813
3 818
3 802
3 8157
3 808
... 90 18
12.11 74 19
12.129 95 2O
12.0251 82 8
11.9963 n.s. 6
11.907 70 21
11.916 50 c 22
11.9237 40 c 23
11.9303 38 23
11.9410 76 24
11.8758 55 25
11.8657 25 26
11.882 65 27
11.96 40 28
11.661 20 e 29
12.10 30 28
a
Nominal composition.
b Value taken from figure.
c From resistivity measurements (zero resistivity).
d Oxygen content Bio.3Sr2YCu2.7OT.125 from chemical analysis.
e From resistivity measurements (zero resistivity); T c = 68 K for Bio.sSr2Yo.8Cu2.706.95 (Ehmann et
aL, 1992).
References: 1, Kolesnikov et al. (1989); 2, Badri and Varadaraju (1995); 3, Michel et al. (199 l b); 4,
Nakajima et al. (1990); 5, Manako et al. (1988); 6, Huv6 et al. (1993a); 7, Martin et al. (1989b); 8,
Shimakawa et al. (1995); 9, Li et al. (1995b); 10, Ganguli et al. (1988); 11, Subramanian et aL
(1988e); 12, Vijayaraghavan et al. (1991); 13, Led6sert et al. (1994); 14, Wahlbeck et al. (1996); 15,
Li and Greenblatt (1989); 16, Subramanian et al. (1990b); 17, Lee and Wang (1995); 18, Rao et al.
(1989); 19, Sundaresan et al. (1995); 20, Manivannan et al. (1993); 21, Rouillon et al. (1990c); 22,
Rouillon et al. (1990b); 23, Maignan et al. (1993a); 24, Minet al. (1994); 25, Liu et aL (1991); 26,
Maeda et al. (1991a); 27, Tang et al. (1991); 28, Beales et al. (1993); 29, Wang et al. (1994).
1212 (Gao.97) 1SrzY
1 Cu207
AB2CD207, tP13, (123) P4/mmm-ihg2dca
-DO2-.C-DO2-OB-A O-OB-
Gao.97Sr2YCu207, n.s., SX, RT, Rw = 0.0528 (Roth et al., 1991)
(46) I2cm (Ima2), a = 5.396, b = 5.484, c = 22.793 A, Z = 4
al + a2,-al + a2, 2e; origin shift 0 -~ 88
Atom WP PS x y
Occ.
Ga 4(b) . .m -0.044
Sr 8(c) 1 0.501
Cu 8(c) 1 -0.001
Y 4(a) 2.. 0.5
O(1) 4(b) . .m 0.596
O(2) 8(c) 1 0.002
0(3) 8(c) 1 0.240
0(4) 8(c) 1 0.234
-0.0691
0.0163
0.0005
0
-0.122
0.044
0.749
0.249
1
4
0.3493
0.4269
1
2
1
4
0.3233
0.4346
0.4372
0.97
(continued)
344
Chapter 8: Crystal Structures of High-T c Superconducting Cuprates
Compound a (A) b (A) c (A) T c (K) Ref.
GaSr2Tmo.6Cao.4Cu207 a 5.369 5.458 22.787 51 1
Gao.97Sr2YCu207 5.396 5.484 22.793 n.s. 2
GaSrzYo.6Cao.4Cu207 5.3821 5.4717 22.805 41 b 3
a
Prepared at 2 GPa; nominal composition.
b Tc .__
73 K for GaSr2Yo.7Cao.3Cu20 7 (Dabrowski et al., 1992).
References: 1, Ono and Tsutsumi (1996); 2, Roth et al. (1991); 3, Babu and Greaves (1995).
1212 HglBa2Cal
Cu206.26
AB2 CD206+6, tP12, (123) P4/mmm-ihg2 d(c)a
-DO2-.C-DO2-OB-A.-OB-
HgBazCaCuzO6.26, a T c -- 114 K, PX, R 8 -- 0.0689 (Putilin et al., 1993b)
(123) P4/mmm, a = 3.85766, e = 12.6562A, Z = 1
Atom WP PS x y
Occ.
Hg l(a) 4/mmm 0 0
1 1
Ba 2(h) 4mm ~
Cu 2(g) 4mm 0 0
1 1
Ca l(d) 4 /mmm ~
1 1
O(1) l(c) 4/mmm ~
0(2) 2(g) 4mm 0 0
1
0(3) 4(i) 2mm . 0
0
0.2197
0.3754
1
_
2
0
0.159
0.389
0.26
a Prepared at 4 GPa.
Compound a (A) c (A)
T c (K) Ref.
Hgo.96Ba2CaCu206.24
Hgo.8Tio.2Ba2CaCu206.2 a
Hgo.gVo.zBazCaCu206.3 a
Hgo.gCro.2BazCaCu206
a
Hgo.8Wo.zBazCaCu206.4 a
Hgo.gMoo.2BazCaCu206.4 a
Hgo.85Reo. 15BazCaCu206+,~ a
Hgo.91BazCao.86Sro.
14Cu206.11
Hgo.4Pro.6Sr2.7Pro.3Cu206+6 a
Hgo.75Nbo.25 Sr2Cao.4Ndo.6Cu206+6 a
Hgo.520Vo.480Sr2Cao.36Yo.64Cu206.81
Hgo.8Moo.zSr2Cao.65Yo.35Cu206+6 a
Hgo.62Reo.38SrzCaCu207.15 f
Hgo.sTlo.sSrzCao.7 Y0.3Cu206+6 a
Hgo.29Pbo.60Sr2Cao.43Yo.48Cu2.2007 a
Hgo.67Bio.33 Sr2Cao.33Yo.67Cu206.6s
Hgo.sBio.sSr2Cao.65Ndo.35Cu206+6 a
3.8552 12.6651 126 1
3.8568 12.581 127 2
3.8692 12.500 128 2
3.8753 12.488 115 2
3.8607 12.661 118 2
3.8602 12.576 127 2
...... 112 3
3.8584 12.6646 1206 4
c 85 5
3.839 11.988 39 a 6
3.8415 11.8514 110 e 7
3.820 11.930 75 d 8
3.8152 12.0621 90 9
3.8 12.0 92 10
3.8166 11.9484 90 g 11
3.80960 12.0157 100 12
3.8093 12.0654 94 13
a
Nominal composition.
b Tc ._.
124 K for sample annealed under
02.
c Space group Pmmm, a - b = 3.8335 and c - 12.264 A; additional reflections indicate superstruc-
ture (B-centered orthorhombic, 2a, b, 2c).
d From resistivity measurements (zero resistivity).
H. Crystallographic Data Sets 345
e From resistivity measurements (onset).
fPrepared at 6 GPa.
g T c
given for Hgo.sPbo.sSrzCao.vYo.3Cu206+ 6.
References: 1, Radaelli
et al.
(1993b); 2, Maignan
et al.
(1995a); 3, Wolters
et al.
(1996); 4, Hur
et al.
(1994); 5, Hervieu
et al.
(1993); 6, Tang
et al.
(1995b); 7, Chmaissem and Sheng (1996); 8, Tang
et al.
(1995a); 9, Chmaissem
et al.
(1996); 10, Liu
et al.
(1993a); 11, Liu
et al.
(1994); 12, Chmaissem
et al.
(1994); 13, Pelloquin
et al.
(1993b).
1212
(Co.47Cuo.42) 1 (Sro.s8Cao.
12)2(Yo.50Cao.26Sro.24)1 Cu206.79
AB2CD207,
tP13, (123)
P4/mmm-ihg2fda
-DOz-.C-DO2-OB-AO"-OB-
Co.47Sr2Cao.5Yo.5Cu2.4206.79, a T c =
22 K, b PN, RT, R e = 0.0509 (Miyazaki
et al.,
1994)
(47)
Pmmm,
a = 3.8319, b-- 3.8501, c- 11.1144A, C Z = 1
al, a2, c
Atom WP PS x y z Occ.
C a l(a)
mmm 0 0 0
0.89
1 1
0.189
Sr e 2(t)
mm2 ~
Cu 2(q)
mm2
0 0 0.356
1 1 1
Yf l(h)
mmm ~ ~
O(1) 2(i)
2mm
0.365 0 0 0.235 g
1 0 0.32
0(2) l(e)
mmm 0
0(3) 4(w) . m. 0.75 0 0.068 0.235 g
0(4) 2(q)
mm2 0 0
0.157 0.53 h
1 0.354 0.58
0(5) 2(r)
mm2 0
1 0.394 0.42
0(6) 2(r)
mm2 0
1 0 0.349 0.58
0(7) 2(s)
ram2
1 0 0.368 0.42
0(8) 2(s)
mm2
a
Carbon and oxygen content
Co.51Sr2Cao.5Yo.5Cu2.4206.92
from chemical analysis.
b Value taken from figure.
c Average structure; additional reflections indicate superstructure.
d C ~- C0.53Cu0.47.
e Sr -- Sr0.ssCa0.12.
fy = Yo.5oCao.z6Sro.24.
g Value taken from carbon content (refined value 0.24).
h Value taken from occupancy of site 0(3) considering occ. 0(4) + 2 • occ. 0(3) -- 1 (refined value
o.7o).
(continued)