Poole Ch.P., Jr. Handbook of Superconductivity

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406 Chapter

1201/2201

Crystal Structures of High-Tc Superconducting Cuprates

C 1Sr2Cu 1 O5/B i2 Sr2Cu 10 6

A3B4D2011, tI40,

(139)

I4/mmm-ge 7ca

-DO2-OB-A O"-OB-DO2-OB-A O-OA-BO-

CBizSr4Cu2011, Tc = 30 K, PX, R = 0.13 (Pelloquin

et al.,

1993a)

(67)

Abram (Cmma),

a = 5.466, b = 5.460, c = 39.500 A, a Z = 4

Fig. 41

a 1 n t- a2, --a 1 + a2, c;

origin shit~ 1 0 88

Atom b WP PS x y

z Occ.

C 4(g)

2mm

0.25 0

Sr(1) 8(m) .m. 0.75 0 0.303

Cu 8(m) .m. 0.25 0 0.345

Sr(2) 8(m) . m. 0.75 0 0.391

Bi 8(m) .m. 0.25 0 0.460

1 1

O(1) 4(e)

. . 2/m 0 ~ -~

1 1 1

0(2) 4(/') .

. 2 /m ~ ~

0(3) 8(m) .m. 0.25 0 0.28

0.35

0(4) 8(j) . .2 0

1 1

0.35

0(5) 8(k) . .2 ~

0(6) 8(m) .m. 0.25 0 0.40

0(7) 8(m) .m. 0.75 0 0.46

0.5

a Average structure; additional reflections indicate incommensurate modulation (q ,~ b*/8.85 to

b*/9).

b o site with occupancy 0.5 (8(n) 0.082 0.168 ~) ignored here (presumed to replace sites O(1) and

0(2) in second refinement).

(continued)

H. Crystallographic Data Sets 407

Compound a (A) c (A) a T c (K) Ref.

HgT12B

a4Cu201 o 3.8584 42.2031 50 1

CBi2Sr4Cu2011 b 30 2

CBi x .sPbo.5 Sr4Cu2011 3.8409 39.444 c 41 d 3

a Space group

I4/mmm.

b Space group Abmm, a- 5.466, b- 5.460 and c = 39.500A; additional reflections indicate

incommensurate modulation (q ~ b*/8.85 to b*/9).

r Additional reflections indicate superstructure (v/2a, V~a, c).

aT c given for CBil.6Pbo.4Sr4Cu2Oll.

References: 1, Martin et aL (1993a); 2, Pelloquin et al. (1993a); 3, Uehara et aL (1993b).

1212/2212

Cu1Ba2Y1Cu206.94/Cu2Ba2Y1Cu208

A3B4C204015 , oS56, (65) Ammm-jSi8ba

-D02-. C-DO2-OB-A O'-OB-D02-. C-DO2-OB-A O'-O' A-BO-

Ba4YzCu7014.94, T c = 91.5K, SX, R w - 0.0282 (Schwer et al., 1993)

(65)

Ammm (Cmmm), a = 3.831, b -- 3.881, c = 50.68 A, Z = 2 Fig. 42

408 Chapter 8:

Crystal Structures of High-Tr Superconducting Cuprates

Atom WP PS x y z Occ.

Cu(1) a 2(a)

mmm 0 0 0

1 1

0.04250

Ba(1) 4(j)

mm2 : :

Cu(2) 4(i)

mm2 0 0

0.08198

1 1

0.11528

Y 4(j)

ram2 : :

Cu(3) 4(i)

mm2 0 0

0.14858

1 1

0.18794

Ba(2) 4(j)

mm2 : :

Cu(4) 4(i)

mm2

0 0 0.23009

1 0

0(1) 2(b)

mmm 0 :

O(2) a 4(i)

mm2

0 0 0.0366

1 0 0.0872

0(3) 4(j)

mm2 :

1 0.0874

0(4) 4(i)

mm2 0 :

1 0 0.1436

0(5) 4(j)

mm2 :

0.1435

0(6) 4(i)

mm2 0 :

0(7) 4(i)

mm2

0 0 0.1940

0.2328

0(8) 4(i)

mm2 0 :

0.94

Full occupation confLrmed.

Compound a (A) b (A) c (A) T c (K)

Ref.

Ba4Nd2Cu7014.85 3.89385 3.90132 50.75013 40 1

Ba4DyECU7014.3 3.85649 3.87713 50.666 69 1

Ba4HoECU7014.36

3.84999 3.87100 50.77142 71 1

Ba4Er2Cu7014.96 3.83501 3.87292 50.53369 79 1

Ba4Y2Cu7014.94 3.831 3.881 50.68 91.5 2

References: 1, Currie

et al.

(1994); 2, Schwer

et al.

(1993).

Ba4Y2Cu7015_ 6 was

first considered as planar defects in

Ba2YCu307_ 6.

structural model based on the replacement of every second AO' (CuO) layer in the

structure of Cu-1212 by two AO' layers was proposed by Zandbergen

et al.

(1988b). Single crystals were obtained during studies on the crystallization of Cu-

1212 at high oxygen pressure (Karpinski

et al.,

1988a) and a structural refinement

was reported by Bordet

et al.

(1988c). The proposed structure

(Ammm)

is an

intergrowth of orthorhombic Cu-1212 and Cu-2212, with a variable oxygen

content in the

additional

layer of the stacking unit of the former type. When 6

differs significantly from zero, the oxygen atoms in this layer are distributed over

two sites (2(b)0 1 0 and 2(d)89 0 0), as in tetragonal Cu-1212. The super-

conducting transition temperature and the orthorhombicity were found to increase

with increasing oxygen content (T c = 92 K for 6 = 0) (Tallon

et al.,

1990) (Figs.

8.45 and 8.46). A critical temperature as high as 95K was reported for

Ba4YECU7Oy by Genoud

et al.

(1991) and associated with an oxygen content

y = 15.15-15.32. According to Schwer

et al.

(1993), the oxygen content cannot

be raised above y = 15 and the high values of T c observed for some samples

should rather be correlated to a partial substitution of copper by carbon or

vacancies on the cation site in the

additional

layer of the Cu-1212 stacking unit.

H. Crystallographic Data Sets 409

Fig. 8.45.

50.95

50.82

50.69

50.56

3.88 !

3.87 -

3.86 -

3.85

3.84 -

3.83 -

3.82

14.0

I ' I ' I ' I ' I ' 'f '

o~'~:~, o_ c

"'~ U ' 0

i .... i

14.2 14.4 14.6 14.8 15.0 15.2 15.4

Ba4Y2Cu7%

Cell parameters vs oxygen content for

Ba4Y2Cu7Oy

(Genoud

et al.,

1992).

Fig. 8.46.

100

' I ' I ' I ' I ' I ' I '

20 , 1 , I , I , _1 , i , I ,

14.0 14.2 14.4 14.6 14.8 15.0 15.2 15.4

Ba4Y2CU7Oy

Superconducting transition temperature vs oxygen content for

Ba4Y2Cu7Oy

(Genoud

et al.,

1992).

410 Chapter 8:

2201/2212

Crystal Structures of High-To Superconducting Cuprates

Bi2Sr2CulO6/Bi2Sr2CalCU208

A4B4CD3014 ,

tP26, (123)

P4/mmm-ihSg4fba

-DO 2-OB-A O-OA-BO-O 2 D-C.-O

2D-BO-OA-AO-OB-

Bi4Sr4CaCu3014 , T c -- 84 K, SX,

R w

: 0.072 (Shepelev

et al.,

1993)

(51)

Pbmm (Pmma),

a = 5.411, b- 5.417, c = 27.75 A, a Z -- 2

Fig. 43

31 + 32, -al + 32, c; origin shift 88 88 0

Atom a WP PS x y

z Occ.

1 0

Cu(1) 2(e)

2mm

0.259

3 0.0612

Sr(1) 4(k) . m. 0.231

Bi(1) 8(/) 1 0.222 0.196 0.1626

Bi(2) 8(/) 1 0.247 0.703 0.2796

1 0.3745

Sr(2) 4(k) .m. 0.236

3 0.4375

Cu(2) 4(k) .m. 0.255

1 1

Ca 2(f)

2mm

0.268 ~

O(1) 2(a)

. .2/m 0 0 0

1 0 0

0(2) 2(c)

. .2/m -~

1 0.087

0(3) 4(k) .m. 0.240

0(4) 8(/) 1 0.051 -0.055 0.200

0(5) 8(/) 1 0.401 0.000 0.243

3 0.347

0(6) 4(k) .m. 0.194

0(7) 4(g) . .2 0 0 0.438

1 0 0.445

0(8) 4(h) . .2

0.5

a Average structure; additional reflections indicate incommensurate modulation (q ~ b*/4.7).

b Atom sites listed in the order D, B, A, A, B, D, C.

H. Crystallographic Data Sets

411

2. Other Intergrowth Structures

1201/1212: The structure of nonsuperconducting B2Sr3Nd2Cu3012 was

refined in space group

P4/nnc

(a = 7.7671, c = 35.8294A) (Amamoto

et al.,

1994). It is an intergrowth of B-1201 and B-1212 stacking units.

1212/1222: The structure of nonsuperconducting Gal.78Sr3.16Nd3.84_

CU4.22016 was

reported to be an intergrowth of Ga-1212 and Ga-1222 stacking

units (a = 5.458, b = 5.535, c = 51.300A) (Ono

et al.,

1995).

1201/1201/2201: The structure of superconducting C2Bi2Sr6Cu3016

(T c =40K) was refined in space group

Fmmm

(a= 5.469, b= 5.483,

c = 54.26A) (Pelloquin

et al.,

1993c). It is an intergrowth of two C-1201

(CSr2CuOs) and one Bi-2201 (Bi2Sr2CuO6) stacking units. A critical temperature

of 54 K was observed for the Pb-containing compound C2(Bi1_xPbx)2Sr6Cu3016

(a = 3.88, c = 54.516 A) (Uehara

et al.,

1993b).

ladder

Sr2Cu305

Sr2Cu305,

oS20, n.s., PN, R e = 0.0263 (Kazakov

et al.,

1997)

(65)

Cmmm,

a = 3.9375, b -- 19.4342, c -- 3.4654 A, Z = 2

Fig. 44

412

Chapter 8:

Atom WP

Crystal Structures of High-T~ Superconducting Cuprates

PS x y z Occ.

Cu(1) 2(a)

Sr 4(/)

Cu(2) 4(i)

0(1) 2(b)

0(2) 4(i)

0(3) 4(i)

mmm 0 0 0

0.1005

m2m ~

m2m 0

0.1987 0

1 0 0

mmm

m2m 0

0.1011 0

1 0.2031 0

m2m

ladder

(Cao.57Lao.43) 14Cu24041

Ca8La6Cu24041, oS316, n.s., SX, R w = 0.044 (Siegrist et al., 1988a)

(66)

Cccm, a = 11.305, b = 12.610, c = 27.608A, Z = 4 Fig. 45a,b

Atom WP PS x y z Occ.

Ca(l) a 8(/) . .m 0.2482

Ca(2) a 16(m) 1 0.2514

Ca(3) a 16(m) 1 0.2489

Ca(4) ~ 16(m) 1 0.2504

Cu(1) 16(m) 1 0.0833

Cu(2) 16(m) 1 0.0831

Cu(3) 16(m) 1 0.0829

Cu(4) 8(/) . .m 0.0835

Cu(5) 4(c)

. .2/m 0

Cu(6) 8(/) . .2 0

Cu(7) 8(i) . .2 0

Cu(8) 8(j) . .2 0

Cu(9) 8(j) . .2 0

Cu(10) 4(b) 222 0

O(1) 8(/) . .m 0.0864

0(2) 16(m) 1 0.0839

0(3) 16(m) 1 0.0834

0(4) 16(m) 1 0.0851

0(5) 8(k) . .2

0(6) 8(k) . .2

0(7) 8(k) . .2

O(8) 4(f) . .2/m

0(9) 16(m) 1 0.1181

0(1 O) 8(g) 2.. O. 1184

0(11) 16(m) 1 0.1211

0(12) 16(m) 1 0.1196

0(13) 16(m) 1 0.1203

O(14) 8(/) . .m 0.1208

0.1168

0.1166

0.2492

0.2549

0.2452

0.2544

0.2662

0.2404

0.2458

0.2425

0.0176

0.0298

0.4957

0.4790

0.4721

0.14256

0.28566

0.42879

0.07139

0.21447

0.35747

0.1010

0.1987

0.0476

0.1490

0.1433

0.2866

0.4288

0.0706

0.2147

0.3578

0.0535

0.3516

0.1037

0.1965

a Ca

= Cao.5714Lao.4286.

(continued)

References 413

Compound a (A) b (A) c (A) T c (K)

Ref.

Ca13.6Sro.4Cu24041.84 a

11.14 12.44 27.02

Ca8La6Cu24041

11.305 12.610 27.608

9 b

n.s.

Prepared at 0.2 GPa.

b Tc

measured at 3.5 GPa.

References: 1, Uehara

et al.

(1996); 2, Siegrist

et al.

(1988a).

Conclusions

The present review provides up-to-date information on the crystal structures of

high-T c superconducting cuprates. The classification is based on widely accepted

concepts with some personal notes, including the derivation of stacking rules and

space groups of ideal structures, and the generation of a high-T c superconductor

family tree.

The compilation contains crystallographic data for more than 400 high-T c

superconductors and related compounds, reported up to 1997, referring to more

than 550 scientific publications. Some 1500 articles dealing with crystal struc-

tures were studied, which, however, represent only a small part of the abundant

literature in the field of high-T c superconductivity. Hence we cannot be assured

that no information was overlooked, in particular concerning thin films and

compounds prepared at high pressure. Review articles and monographs were

consulted, but all data reported here were taken from the original publications.

Acknowledgment

We thank Dr. Karin Cenzual for useful discussions and critical reading of the

manuscript.

References

S. Adachi, O. Inoue, S. Kawashima, H. Adachi, Y. Ichikawa, K. Setsune, and K. Wasa,

Physica C

168

1-7 (1990a).

S. Adachi, K. Setsune, and K. Wasa,

Jpn. J. Appl. Phys.

29, L890-L892 (1990b).

S. Adachi, A. Nara, and H. Yamauchi,

Physica C

201, 403-406 (1992).

S. Adachi, H. Yamauchi, S. Tanaka, and N. M6ri,

Physica C

212, 164-168 (1993).

J. Akimitsu, A. Yamazaki, H. Sawa, and H. Fujiki,

Jpn. J Appl. Phys.

26, L2080-L2081 (1987).

J. Akimitsu, S. Suzuki, M. Watanabe, and H. Sawa,

Jpn. J. Appl. Phys.

27, L1859-L1860 (1988).

J. Akimitsu, M. Uehara, M. Ogawa, H. Nakata, K. Tomimoto, Y. Miyazaki, H. Yamane, T. Hirai, K.

Kinoshita, and Y. Matsui,

Physica C

201, 320-324 (1992).

J. Akimoto, Y. Oosawa, K. Tokiwa, M. Hirabayashi, and H. Ihara,

Physica C

242, 360-364 (1995).

M. A.

Alario-Franco, E Bordet, J. J. Capponi, C. Chaillout, J. Chenavas, T. Fournier, M. Marezio, S. de

Brion, B. Souletie, A. Sulpice, J. L. Tholence, C. Colliex, R. Argoud, J. L. Baldonedo, M. E Gorius,

and M. Perroux,

Physica C

235--240, 975-976 (1994a).

414

Chapter 8: Crystal Structures of High-T~ Superconducting Cuprates

M. A.

Alario-Franco, C. Chaillout, J. J. Capponi, J.-L. Tholence, and B. Souletie, Physica C 222, 52-56

(1994b).

E. T. Alexandre, S. M. Loureiro, E. V. Antipov, P. Bordet, S. de Brion, J. J. Capponi, and M. Marezio,

Physica C 245, 207-211 (1995).

M. A1-Mamouri, P. P. Edwards, C. Greaves, and M. Slaski, Nature 369, 382-384 (1994).

J. A. Alonso and G. Lapertot, Physica C 250, 93-100 (1995).

Y. Amamoto, H. Yamane, T. Oku, Y. Miyazaki, and T. Hirai, Physica C 227, 245-253 (1994).

M. T. Anderson, K. R. Poeppelmeier, J.-P. Zhang, H.-J. Fan, and L. D. Marks, Chem. Mater. 4, 1305-

1313 (1992).

E. V. Antipov, S. M. Loureiro, C. Chaillout, J. J. Capponi, E Bordet, J. L. Tholence, S. N. Putilin, and M.

Marezio, Physica C 215, 1-10 (1993).

M. A. G. Aranda, D. C. Sinclair, and J. E Attfield, Physica C 221,304-310 (1994).

D. N. Argyriou, J. D. Jorgensen, R. L. Hitterman, Z. Hiroi, N. Kobayashi, and M. Takano, Phys. Rev. B

51, 8434-8437 (1995).

T. Arima, Y. Tokura, H. Takagi, S. Uchida, R. Beyers, and J. B. Torrance, Physica C 168, 79-84

(1990).

A. R. Armstrong and P. P. Edwards, J. Solid State Chem. 98, 432-436 (1992).

H. Asano, T. Ishigaki, and K. Takita, Jpn. J. Appl. Phys. 26, L1064-L1065 (1987a).

H. Asano, K. Takita, T. Ishigaki, H. Akinaga, H. Katoh, K. Masuda, E Izumi, and N. Watanabe, Jpn. J.

Appl. Phys. 26, L1341-L1343 (1987b).

H. Asano, K. Takita, H. Katoh, H. Akinaga, T. Ishigaki, M. Nishino, M. Imai, and K. Masuda, Jpn. J.

Appl. Phys. 26, L1410-L1412 (1987c).

H. Asano, Y. Yokoyama, M. Nishino, H. Katoh, H. Akinaga, and K. Takita, Mod. Phys. Lett. B 2, 583-

588 (1988).

B. Aurivillius, Arkiv Kemi 1,463-480 (1950).

J. D. Axe, A. H. Moudden, D. Hohlwein, D. E. Cox, K. M. Mohanty, A. R. Moodenbaugh, and Y. Xu,

Phys. Rev. Lett. 62, 2751-2754 (1989).

M. Azuma, Z. Hiroi, M. Takano, Y. Bando, and Y. Takeda, Nature 356, 775-776 (1992).

T. G. N. Babu and C. Greaves, J. Superconduct. 8, 21-25 (1995).

T. G. N. Babu, D. J. Fish, and C. Greaves, J. Mater. Chem. 1, 677-679 (1991).

V. Badri and U. V. Varadaraju, Solid State Commun. 93, 1003-1007 (1995).

D. Balz, Naturwissenschafien 40, 241 (1953).

L. Barbey, N. Nguyen, A. Ducouret, V. Caignaert, J. M. Gren6che, and B. Raveau, J. Solid State Chem.

115, 514-520 (1995).

T. Barth, Norsk Geol. Tidss~ 8, 201-219 (1925).

L. Bauernfeind, W. Widder, and H. E Braun, Physica C 254, 151-158 (1995).

T. P. Beales, C. Dineen, S. R. Hall, M. R. Harrison, and J. M. Parberry, Physica C 207, 1-8 (1993).

J. G. Bednorz and K. A. Mfiller, Z Phys. B 64, 189-193 (1986).

E Beech, S. Miraglia, A. Santoro, and R. S. Roth, Phys. Rev. B 35, 8778-8781 (1987).

M. A. Beno, L. Soderholm, D. W. Capone II, D. G. Hinks, J. D. Jorgensen, J. D. Grace, I. K. Schuller, C.

U. Segre, and K. Zhang, Appl. Phys. Lett. 51, 57-59 (1987).

E J. M. Benschop, W. T. Fu, and W. J. A. Maaskant, Physica C 184, 311-315 (1991).

E J. M. Benschop, R. B. Helmholdt, and W. J. A. Maaskant, Physica C 227, 129-142 (1994).

P. Berastegui, L.-G. Johansson, M. K/ill, and L. B6rjesson, Physica C 204, 147-154 (1992).

A. I. Beskrovnyi, M. Dlouhfi, Z. Jirfik, and S. Vratislav, Physica C 171, 19-24 (1990a).

A. I. Beskrovnyi, M. Dlouhfi, Z. Jirfik, S. Vratislav, and E. Pollert, Physica C 166, 79-86 (1990b).

A. I. Beskrovnyi, S. DurEok, J, Hejtmfinek, Z. Jifftk, E. Pollert, and I. G. Shelkova, Physica C 222, 375-

385 (1994).

R. Beyers, G. Lim, E. M. Engler, R. J. Savoy, T. M. Shaw, T. R. Dinger, W. J. Gallagher, and R. L.

Sandstrom, Appl. Phys. Lett. 50, 1918-1920 (1987).

S. J. L. Billinge and T. Egami, Phys. Rev. B 47, 14386-14405 (1993).

References 415

H. A. Blackstead, D. B. Chrisey, J. D. Dow, J. S. Horwitz, A. E. Klunzinger, and D. B. Pulling,

Phys.

Lett. A

207, 109-112 (1995).

E Bordet, J. J. Capponi, C. Chaillout, J. Chenavas, A. W. Hewat, E. A. Hewat, J. L. Hodeau, M. Marezio,

J. L. Tholence, and D. Tranqui,

Physica C

153-155, 623-624 (1988a).

E Bordet, J. J. Capponi, C. Chaillout, J. Chenavas, A. W. Hewat, E. A. Hewat, J. L. Hodeau, M. Marezio,

J. L. Tholence, and D. Tranqui,

Physica C

156, 189-192 (1988b).

P. Bordet, C. Chaillout, J. Chenavas, J. L. Hodeau, M. Marezio, J. Karpinski, and E. Kaldis,

Nature

334,

596-598 (1988c).

P. Bordet, J. J. Capponi, C. Chaillout, D. Chateigner, J. Chenavas, Th. Foumier, J. L. Hodeau, M.

Marezio, M. Perroux, G. Thomas, and A. Varela,

Physica C

193, 178-188 (1992).

E Bordet, S. Le Floch, J. J. Capponi, C. Chaillout, M. E Gorius, M. Marezio, J. L. Tholence, and E G.

Radaelli,

Physica C

262, 151-158 (1996).

D. Bourgault, C. Martin, C. Michel, M. Hervieu, J. Provost, and B. Raveau,

J. Solid State Chem.

78,

326-328 (1989).

M. Braden, W. Paulus, A. Cousson, P. Vigoureux, G. Heger, A. Goukassov, P. Bourges, and D.

Petitgrand,

Europhys. Lett.

25, 625-630 (1994).

J. E Bringley, B. A. Scott, S. J. La Placa, R. E Boehme, T. M. Shaw, M. W. McElfresh, S. S. Trail, and D.

E. Cox,

Nature

347, 263-265 (1990).

J. E Bringley, B. A. Scott, S. J. La Placa, T. R. McGuire, E Mehran, M. W. McElfresh, and D. E. Cox,

Phys. Rev. B

47, 15269-15275 (1993).

E Burlet, V. P. Plakthy, C. Matin, and J. Y. Henry,

Phys. Lett. A

167, 401-404 (1992).

R. H. Buttner and E. N. Maslen,

Acta Cryst. B

48, 764-769 (1992).

V. Caignaert, I. Mirebeau, E Bour4e, N. Nguyen, A. Ducouret, J.-M. Gren6che, and B. Raveau,

J. Solid

State Chem.

114, 24-35 (1995).

G. Calestani, C. Rizzoli, M. G. Francesconi, and G. D. Andreetti,

Physica C

161,598-606 (1989).

G. Calestani, M. G. Francesconi, G. Salsi, and G. D. Andreetti,

Physica C

197, 283-298 (1992).

J. J. Capponi, C. Chaillout, A. W. Hewat, P. Lejay, M. Marezio, N. Nguyen, B. Ravaeu, J. L.

Soubeyroux, J. L. Tholence, and R. Toumier,

Europhys. Lett.

3, 1301-1307 (1987).

W. Carrilo-Cabrera and W. G6pel,

Physica C

161,373-389 (1989).

R. J. Cava, B. Batlogg, C. H. Chen, E. A. Rietman, S. Zahurak, and D. Werder,

Phys. Rev. B

36, 5719-

5722 (1987a).

R. J. Cava, B. Batlogg, R. B. van Dover, D. W. Murphy, S. Sunshine, T. Siegrist, J. P. Remeika, E. A.

Rietman, S. Zahurak, and G. P. Espinosa,

Phys. Rev. Lett.

58, 1676-1679 (1987b).

R. J. Cava, A. Santoro, D. W. Johnson, Jr., and W. W. Rhodes,

Phys. Rev. B

35, 6716-6720

(1987c).

R. J. Cava, R. B. van Dover, B. Batlogg, and E. A. Rietman,

Phys. Rev. Lett.

58, 408-410 (1987d).

R. J. Cava, B. Batlogg, J. J. Krajewski, L. W. Rupp, L. E Schneemeyer, T. Siegrist, R. B. Van Dover, E

Marsh, W. E Peck, Jr., P. K. Gallagher, S. H. Glarum, J. H. Marshall, R. C. Farrow, J. V. Waszczak, R.

Hull, and P. Trevor,

Nature

336, 211-214 (1988).

R. J. Cava, M. Marezio, J. J. Krajewski, W. E Peck, Jr., A Santoro, and E Beech,

Physica C

157, 272-

278 (1989).

R. J. Cava, B. Batlogg, R. B. van Dover, J. J. Krajewski, J. V. Waszczak, R. M. Fleming, W. E Peck, Jr.,

L. W. Rupp, Jr., P. Marsh, A. C. W. P. James, and L. E Schneemeyer,

Nature

345, 602-604 (1990a).

R. J. Cava, A. Santoro, J. J. Krejewski, R. M. Fleming, J. V. Waszczak, W. E Peck, Jr., and P. Marsh,

Physica C

172, 138-142 (1990b).

R. J. Cava, R. B. Van Dover, B. Batlogg, J. J. Krajewski, L. E Schneemeyer, T. Siegrist, B. Hessen, S. H.

Chen, W. E Peck, Jr., and L. W. Rupp, Jr.,

Physica C

185-189, 180-183 (1991).

R. J. Cava, J. J. Krajewski, H. Takagi, H. W. Zandbergen, R. B. Van Dover, W. E Peck, Jr., and B.

Hessen,

Physica C

191,237-242 (1992).

C. Chaillout, M. A. Alario-Franco, J. J. Capponi, J. Chenavas, J. L. Hodeau, and M. Marezio,

Phys. Rev.

B 36, 7118-7120 (1987).