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Modulated structure of an 800 A epitactic film of the superconductor Bi2Sr2CaCu2O8 as studied by synchrotron radiation

Authors:

Lee, P.; Graafsma, H.; Gao, Y.; Sheu, H.S.; Coppens, P.; Golden, S.J.; Lange, F.F.

Journal:

Acta Cryst. A 47 57-59 (1991)

DOI:

https://doi.org/10.1107/S0108767390012788

B-IncStrDB ID: 352ENpKT7 Entry date: 2010-11-08 Last revision: 2021-12-30

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Bi2Sr2

Chemical data

Structural Formula: Bi2 Sr2 Ca Cu2 O8 [ Help ]

Structural Formula Sum: Bi2.23 Ca0.87 Cu2 O8 Sr1.55 [ Help ]

Formula weight: 891.8 Da [ Help ]

Crystallographic data and experimental details

a: 5.420(1) Å [ Help ]

b: 5.409(2) Å [ Help ]

c: 30.76(1) Å [ Help ]

α: 90 ° [ Help ]

β: 90 ° [ Help ]

γ: 90 ° [ Help ]

Volume: 901.8(5) Å3 [ Help ]

Z: 4 [ Help ]

μ: 80.66 mm-1 [ Help ]

Cell measurement temperature: 293 K [ Help ]

Crystal system: orthorhombic [ Help ]

Superspace group name (WJJ): M:A 2 a a:1 1 1 [ Help ]

Superspace group name: X2aa(α00)000 [ Help ]

Symmetry operations of the superspace group: [ Help ]

Operation code Operation in algebraic form
1 x1,x2,x3,x4
2 x1,-x2,-x3,x4
3 1/2+x1,-x2,x3,x4
4 1/2+x1,x2,-x3,x4
5 x1,1/2+x2,1/2+x3,1/2+x4
6 x1,1/2-x2,1/2-x3,1/2+x4
7 1/2+x1,1/2-x2,1/2+x3,1/2+x4
8 1/2+x1,1/2+x2,1/2-x3,1/2+x4

Space group name (H-M): A 2 a a [ Help ]

Modulation dimension: 1 [ Help ]

Experimental remarks: Sample: thin film (average thickness 800°A). Twinned sample: 2 domains. Wave vector estimated from: 1) Petricek, Gao, Lee & Coppens Phys. Rev. (1990) B42, 387-392 2) Gao, Coppens, Cox & Moodenbaugh Acta Cryst. (1993) A49, 141-148 [ Help ]

Measured independent wave vectors: [ Help ]

Wave vector id q_x q_y q_z
1 0.21 0 0

Refinement details

Refinement remarks: WARNING: The published displacement parameters have been converted to relative units. The calculated standard uncertainties (s.u.) have been based uniquely on the published ones without considering the s.u. of any other quantity involved in such conversion. [ Help ]

Modulation functions description: Displacive modulation:Fourier series. Up to 2nd-order harmonics. [ Help ]

Structure factors calc. details: Bessel functions [ Help ]

Nb. of observed reflections: 419 [ Help ]

R(obs): 0.117 [ Help ]

wR(obs): 0.131 [ Help ]

Structural Information

Average Structure: [ Help ]

Site description Atom site label Atom symbol Symmetry multiplicity Occupancy x y z Uiso/equiv ADP type
Bi on Bi sites Bi/Bi Bi 8 0.95(3) 0.497(4) 0.2323(7) 0.0524(1) ? Uani
Bi on Sr sites Bi/Sr Bi 8 0.10(2) 0 0.2516(8) 0.1408(3) ? Uani
Sr on Sr sites Sr/Sr Sr 8 0.775 0 0.2516(8) 0.1408(3) ? Uani
. Cu Cu 8 1 0.5 0.249(1) 0.1973(4) ? Uani
Bi on Ca sites Bi/Ca Bi 4 0.13(2) 0 0.25 0.25 ? Uani
Ca on Ca sites Ca/Ca Ca 4 0.87 0 0.25 0.25 ? Uani
. O1 O 8 1 0.75 0 0.198(1) 0.01 Uiso
. O2 O 8 1 0.25 0.5 0.201(1) 0.01 Uiso
. O3 O 8 1 0.52(1) 0.304(9) 0.109(2) 0.01 Uiso
. O4 O 8 1 -0.02(2) 0.196(9) 0.057(2) 0.01 Uiso

Fourier Wave Vectors (explicit: q_x,q_y,q_z or coefficients: q_1,q_2,...): [ Help ]

Wave vector code q_x q_y q_z
1 0.21 0 0
2 0.42 0 0

Definition of the displacive (translational) Fourier series: [ Help ]

Modulation code Atom site label Displacement axis Wave vector code
Bi/Bix1 Bi/Bi x 1
Bi/Bix2 Bi/Bi x 2
Bi/Biy1 Bi/Bi y 1
Bi/Biy2 Bi/Bi y 2
Bi/Biz1 Bi/Bi z 1
Bi/Biz2 Bi/Bi z 2
Bi/Srx1 Bi/Sr x 1
Bi/Srx2 Bi/Sr x 2
Bi/Sry1 Bi/Sr y 1
Bi/Sry2 Bi/Sr y 2
Bi/Srz1 Bi/Sr z 1
Bi/Srz2 Bi/Sr z 2
Sr/Srx1 Sr/Sr x 1
Sr/Srx2 Sr/Sr x 2
Sr/Sry1 Sr/Sr y 1
Sr/Sry2 Sr/Sr y 2
Sr/Srz1 Sr/Sr z 1
Sr/Srz2 Sr/Sr z 2
Bi/Cax1 Bi/Ca x 1
Bi/Cax2 Bi/Ca x 2
Bi/Cay1 Bi/Ca y 1
Bi/Cay2 Bi/Ca y 2
Bi/Caz1 Bi/Ca z 1
Bi/Caz2 Bi/Ca z 2
Ca/Cax1 Ca/Ca x 1
Ca/Cax2 Ca/Ca x 2
Ca/Cay1 Ca/Ca y 1
Ca/Cay2 Ca/Ca y 2
Ca/Caz1 Ca/Ca z 1
Ca/Caz2 Ca/Ca z 2
Cux1 Cu x 1
Cux2 Cu x 2
Cuy1 Cu y 1
Cuy2 Cu y 2
Cuz1 Cu z 1
Cuz2 Cu z 2

Displacive (translational) Fourier coefficients: [ Help ]

Modulation code Cosine coefficient Sine coefficient
Bi/Bix1 0.004(6) 0.0629(13)
Bi/Bix2 0.002(4) 0.0055(18)
Bi/Biy1 -0.0092(18) 0.0018(18)
Bi/Biy2 0.009(4) 0.007(6)
Bi/Biz1 -0.0049(2) -0.0010(7)
Bi/Biz2 -0.0010(3) -0.0013(3)
Bi/Srx1 0 0.0461(18)
Bi/Srx2 0 0.018(4)
Bi/Sry1 0.0037(18) 0
Bi/Sry2 -0.002(7) 0
Bi/Srz1 -0.0072(3) 0
Bi/Srz2 -0.0013(7) 0
Sr/Srx1 0 0.0461(18)
Sr/Srx2 0 0.018(4)
Sr/Sry1 0.0037(18) 0
Sr/Sry2 -0.002(7) 0
Sr/Srz1 -0.0072(3) 0
Sr/Srz2 -0.0013(7) 0
Bi/Cax1 0 0
Bi/Cax2 0 -0.002(6)
Bi/Cay1 0.006(4) 0
Bi/Cay2 0 0
Bi/Caz1 -0.0088(7) 0
Bi/Caz2 0 0
Ca/Cax1 0 0
Ca/Cax2 0 -0.002(6)
Ca/Cay1 0.006(4) 0
Ca/Cay2 0 0
Ca/Caz1 -0.0088(7) 0
Ca/Caz2 0 0
Cux1 0 0.0111(18)
Cux2 0 0.000(4)
Cuy1 -0.002(4) 0
Cuy2 -0.002(13) 0
Cuz1 -0.0091(7) 0
Cuz2 -0.0007(7) 0

ADP components: [ Help ]

Atom site label Atom site symbol U11 U22 U33 U12 U13 U23
Bi/Bi Bi 0.102(6) 0.050(4) 0.060(3) -0.018(6) 0.007(6) 0.000(2)
Bi/Sr Bi 0.042(6) 0.035(5) 0.084(6) 0 0 0.003(3)
Sr/Sr Sr 0.042(6) 0.035(5) 0.084(6) 0 0 0.003(3)
Cu Cu 0.004(7) 0.028(8) 0.082(9) 0 0 0.003(4)
Bi/Ca Bi 0.057(11) 0.023(9) 0.076(10) 0 0 0.005(5)
Ca/Ca Ca 0.057(11) 0.023(9) 0.076(10) 0 0 0.005(5)