Mean-square atomic displacements in lanthanum triiron cobalt dodecaantimonide, determined as a function of temperature using single-crystal neutron diffraction, show that the La atom exhibits an anomalously large displacement at room temperature, Ueq = 0.0196 (9) Å2, because it is too small to fill the atomic cage formed by the corner-linked octahedral framework of M4Sb12, M = Fe, Co. Site-occupancy refinements show 25% vacancies on the La site and an actual Fe:Co ratio of 2.17:1. Analysis of the temperature dependence of the atomic displacements identifies a significant temperature-independent component for the La atom ascribed to static disorder, which amounts to 19% of the room-temperature value. The large-amplitude rattling of the La atom can be effectively linked to the dramatic decrease of the lattice contribution to the thermal conductivity, which is a key factor for improving the thermoelectric behavior of these materials. This structure-property relationship offers a new paradigm for the exploration of thermoelectric materials.
Supporting information
| Crystallographic Information File (CIF) Contains datablocks global, phase1, phase2, phase3, phase4, phase5, phase6, phase7, phase8, phase9 |
| Structure factor file (SHELXL table format) Supplementary material |
| Structure factor file (SHELXL table format) Supplementary material |
| Structure factor file (SHELXL table format) Supplementary material |
| Structure factor file (SHELXL table format) Supplementary material |
| Structure factor file (SHELXL table format) Supplementary material |
| Structure factor file (SHELXL table format) Supplementary material |
| Structure factor file (SHELXL table format) Supplementary material |
| Structure factor file (SHELXL table format) Supplementary material |
| Structure factor file (SHELXL table format) Supplementary material |
For all compounds, data collection: UCLA Crystallographic Computing Package (Strouse 1994); cell refinement: UCLA Crystallographic Computing Package - Program Least (Strouse 1994); data reduction: UCLA Crystallographic Computing Package - Program Reduce, Lehmann-Larson algorithm (Strouse 1994); program(s) used to refine structure: GSAS (Larson & Von Dreele 1986); molecular graphics: ATOMS (Dowty 1993).
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.901 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0971 (6) Å | µ = 0.02 mm−1 |
V = 752.85 Å3 | T = 295 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
1405 measured reflections | k = 0→16 |
463 independent reflections | l = 0→16 |
321 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.046 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.045 | (Δ/σ)max < 0.001 |
wR(F2) = 0.035 | Δρmax = 1.05 e Å−3 |
S = 1.31 | Δρmin = −0.48 e Å−3 |
321 reflections | Extinction correction: B-C type I Gaussian isotropic |
13 parameters | Extinction coefficient: 2.32E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0196 (9) | .743 (17) |
Fe | 0.25 | 0.25 | 0.25 | 0.0053 (1) | .685 (8) |
Co | 0.25 | 0.25 | 0.25 | 0.0053 (1) | .315 (8) |
Sb | 0.0 | 0.33678 (9) | 0.16021 (8) | 0.0074 (3) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0197 (9) | 0.0197 (9) | 0.0197 (9) | 0.0 | 0.0 | 0.0 |
Fe | 0.00535 (18) | 0.00535 (18) | 0.00535 (18) | 0.00047 (16) | 0.00047 (16) | 0.00047 (16) |
Co | 0.00535 (18) | 0.00535 (18) | 0.00535 (18) | 0.00047 (16) | 0.00047 (16) | 0.00047 (16) |
Sb | 0.0052 (3) | 0.0100 (3) | 0.0070 (3) | 0.0 | 0.0 | 0.0013 (3) |
Geometric parameters (Å, º) top
La—Sb | 3.3927 (9) | Sb—Sb | 2.969 (1) |
Fe,Co—Sb | 2.5422 (4) | Sb—Sb | 3.4294 (8) |
Sb—Sb | 2.914 (1) | | |
| | | |
Sb—Fe,Co—Sb | 95.17 (2) | Fe,Co—Sb—Fe,Co | 126.91 (3) |
Sb—Fe,Co—Sb | 84.83 (2) | | |
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.931 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0854 (11) Å | µ = 0.02 mm−1 |
V = 749.95 Å3 | T = 200 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
1486 measured reflections | k = 0→16 |
470 independent reflections | l = 0→16 |
316 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.051 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.048 | (Δ/σ)max < 0.001 |
wR(F2) = 0.036 | Δρmax = 0.82 e Å−3 |
S = 1.34 | Δρmin = −0.43 e Å−3 |
316 reflections | Extinction correction: B-C type I Gaussian isotropic |
11 parameters | Extinction coefficient: 2.2E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0151 (5) | .743 |
Fe | 0.25 | 0.25 | 0.25 | 0.0042 (1) | .686 |
Co | 0.25 | 0.25 | 0.25 | 0.0042 (1) | .314 |
Sb | 0.0 | 0.33668 (9) | 0.15998 (8) | 0.0057 (3) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0152 (6) | 0.0152 (6) | 0.0152 (6) | 0.0 | 0.0 | 0.0 |
Fe | 0.00425 (15) | 0.00425 (15) | 0.00425 (15) | 0.00039 (18) | 0.00039 (18) | 0.00039 (18) |
Co | 0.00425 (15) | 0.00425 (15) | 0.00425 (15) | 0.00039 (18) | 0.00039 (18) | 0.00039 (18) |
Sb | 0.0039 (3) | 0.0083 (3) | 0.0049 (3) | 0.0 | 0.0 | 0.0008 (3) |
Geometric parameters (Å, º) top
La—Sb | 3.386 (1) | Sb—Sb | 2.967 (1) |
Fe,Co—Sb | 2.5393 (4) | Sb—Sb | 3.4272 (9) |
Sb—Sb | 2.907 (1) | | |
| | | |
Sb—Fe,Co—Sb | 95.11 (2) | Fe,Co—Sb—Fe,Co | 126.88 (3) |
Sb—Fe,Co—Sb | 84.88 (2) | | |
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.931 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0857 (11) Å | µ = 0.02 mm−1 |
V = 750.02 Å3 | T = 150 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
1492 measured reflections | k = 0→16 |
471 independent reflections | l = 0→16 |
318 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.053 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.045 | (Δ/σ)max < 0.001 |
wR(F2) = 0.036 | Δρmax = 1.11 e Å−3 |
S = 1.35 | Δρmin = −0.63 e Å−3 |
318 reflections | Extinction correction: B-C type I Gaussian isotropic |
11 parameters | Extinction coefficient: 2.2E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0127 (5) | .743 |
Fe | 0.25 | 0.25 | 0.25 | 0.0032 (1) | .686 |
Co | 0.25 | 0.25 | 0.25 | 0.0032 (1) | .314 |
Sb | 0.0 | 0.33659 (9) | 0.15999 (9) | 0.0046 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0127 (5) | 0.0127 (5) | 0.0127 (5) | 0.0 | 0.0 | 0.0 |
Fe | 0.00328 (15) | 0.00328 (15) | 0.00328 (15) | 0.00003 (17) | 0.00003 (17) | 0.00003 (17) |
Co | 0.00328 (15) | 0.00328 (15) | 0.00328 (15) | 0.00003 (17) | 0.00003 (17) | 0.00003 (17) |
Sb | 0.0031 (3) | 0.0067 (3) | 0.0041 (3) | 0.0 | 0.0 | 0.0002 (3) |
Geometric parameters (Å, º) top
La—Sb | 3.3861 (9) | Sb—Sb | 2.969 (1) |
Fe,Co—Sb | 2.5391 (4) | Sb—Sb | 3.4276 (9) |
Sb—Sb | 2.907 (1) | | |
| | | |
Sb—Fe,Co—Sb | 95.09 (2) | Fe,Co—Sb—Fe,Co | 126.90 (3) |
Sb—Fe,Co—Sb | 84.90 (2) | | |
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.942 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0813 (5) Å | µ = 0.02 mm−1 |
V = 748.93 Å3 | T = 125 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
484 measured reflections | k = 0→16 |
337 independent reflections | l = 0→16 |
264 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.024 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.062 | (Δ/σ)max < 0.001 |
wR(F2) = 0.043 | Δρmax = 0.44 e Å−3 |
S = 1.26 | Δρmin = −0.25 e Å−3 |
264 reflections | Extinction correction: B-C type I Gaussian isotropic |
11 parameters | Extinction coefficient: 2.5E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0107 (6) | .743 |
Fe | 0.25 | 0.25 | 0.25 | 0.0030 (2) | .686 |
Co | 0.25 | 0.25 | 0.25 | 0.0030 (2) | .314 |
Sb | 0.0 | 0.33679 (12) | 0.16008 (11) | 0.0039 (4) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0108 (7) | 0.0108 (7) | 0.0108 (7) | 0.0 | 0.0 | 0.0 |
Fe | 0.0031 (2) | 0.0031 (2) | 0.0031 (2) | 0.0002 (3) | 0.0002 (3) | 0.0002 (3) |
Co | 0.0031 (2) | 0.0031 (2) | 0.0031 (2) | 0.0002 (3) | 0.0002 (3) | 0.0002 (3) |
Sb | 0.0027 (3) | 0.0058 (3) | 0.0031 (3) | 0.0 | 0.0 | 0.0014 (4) |
Geometric parameters (Å, º) top
La—Sb | 3.386 (1) | Sb—Sb | 2.964 (2) |
Fe,Co—Sb | 2.5382 (5) | Sb—Sb | 3.424 (1) |
Sb—Sb | 2.907 (2) | | |
| | | |
Sb—Fe,Co—Sb | 95.15 (3) | Fe,Co—Sb—Fe,Co | 126.88 (4) |
Sb—Fe,Co—Sb | 84.84 (3) | | |
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.943 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0809 (4) Å | µ = 0.02 mm−1 |
V = 748.83 Å3 | T = 100 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
1400 measured reflections | k = 0→16 |
459 independent reflections | l = 0→16 |
330 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.041 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.041 | (Δ/σ)max < 0.001 |
wR(F2) = 0.031 | Δρmax = 0.43 e Å−3 |
S = 1.23 | Δρmin = −0.42 e Å−3 |
330 reflections | Extinction correction: B-C type I Gaussian isotropic |
11 parameters | Extinction coefficient: 2.4E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0100 (3) | .743 |
Fe | 0.25 | 0.25 | 0.25 | 0.0032 (1) | .686 |
Co | 0.25 | 0.25 | 0.25 | 0.0032 (1) | .314 |
Sb | 0.0 | 0.33678 (7) | 0.15995 (7) | 0.0039 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0100 (4) | 0.0100 (4) | 0.0100 (4) | 0.0 | 0.0 | 0.0 |
Fe | 0.00320 (13) | 0.00320 (13) | 0.00320 (13) | 0.00051 (14) | 0.00051 (14) | 0.00051 (14) |
Co | 0.00320 (13) | 0.00320 (13) | 0.00320 (13) | 0.00051 (14) | 0.00051 (14) | 0.00051 (14) |
Sb | 0.00250 (19) | 0.0058 (2) | 0.0032 (2) | 0.0 | 0.0 | 0.0005 (2) |
Geometric parameters (Å, º) top
La—Sb | 3.3857 (7) | Sb—Sb | 2.964 (1) |
Fe,Co—Sb | 2.5384 (2) | Sb—Sb | 3.4254 (7) |
Sb—Sb | 2.904 (1) | | |
| | | |
Sb—Fe,Co—Sb | 95.13 (2) | Fe,Co—Sb—Fe,Co | 126.84 (2) |
Sb—Fe,Co—Sb | 84.86 (2) | | |
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.942 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0814 (5) Å | µ = 0.02 mm−1 |
V = 748.95 Å3 | T = 75 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
1390 measured reflections | k = 0→16 |
459 independent reflections | l = 0→16 |
328 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.042 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.042 | (Δ/σ)max < 0.001 |
wR(F2) = 0.034 | Δρmax = 0.58 e Å−3 |
S = 1.36 | Δρmin = −0.41 e Å−3 |
328 reflections | Extinction correction: B-C type I Gaussian isotropic |
11 parameters | Extinction coefficient: 2.3E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0088 (4) | .743 |
Fe | 0.25 | 0.25 | 0.25 | 0.0030 (1) | .686 |
Co | 0.25 | 0.25 | 0.25 | 0.0030 (1) | .314 |
Sb | 0.0 | 0.33671 (8) | 0.15994 (7) | 0.0034 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0089 (4) | 0.0089 (4) | 0.0089 (4) | 0.0 | 0.0 | 0.0 |
Fe | 0.00303 (14) | 0.00303 (14) | 0.00303 (14) | 0.00012 (15) | 0.00012 (15) | 0.00012 (15) |
Co | 0.00303 (14) | 0.00303 (14) | 0.00303 (14) | 0.00012 (15) | 0.00012 (15) | 0.00012 (15) |
Sb | 0.0026 (2) | 0.0052 (2) | 0.0024 (2) | 0.0 | 0.0 | 0.0006 (2) |
Geometric parameters (Å, º) top
La—Sb | 3.3852 (8) | Sb—Sb | 2.965 (1) |
Fe,Co—Sb | 2.5384 (3) | Sb—Sb | 3.4260 (7) |
Sb—Sb | 2.904 (1) | | |
| | | |
Sb—Fe,Co—Sb | 95.11 (2) | Fe,Co—Sb—Fe,Co | 126.86 (2) |
Sb—Fe,Co—Sb | 84.88 (2) | | |
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.935 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0839 (6) Å | µ = 0.02 mm−1 |
V = 749.57 Å3 | T = 50 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
1390 measured reflections | k = 0→16 |
459 independent reflections | l = 0→16 |
329 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.041 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.039 | (Δ/σ)max < 0.001 |
wR(F2) = 0.031 | Δρmax = 0.52 e Å−3 |
S = 1.24 | Δρmin = −0.46 e Å−3 |
329 reflections | Extinction correction: B-C type I Gaussian isotropic |
11 parameters | Extinction coefficient: 2.2E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0078 (3) | .743 |
Fe | 0.25 | 0.25 | 0.25 | 0.0028 (1) | .686 |
Co | 0.25 | 0.25 | 0.25 | 0.0028 (1) | .314 |
Sb | 0.0 | 0.33684 (7) | 0.16002 (7) | 0.0031 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0078 (4) | 0.0078 (4) | 0.0078 (4) | 0.0 | 0.0 | 0.0 |
Fe | 0.00283 (13) | 0.00283 (13) | 0.00283 (13) | 0.00030 (14) | 0.00030 (14) | 0.00030 (14) |
Co | 0.00283 (13) | 0.00283 (13) | 0.00283 (13) | 0.00030 (14) | 0.00030 (14) | 0.00030 (14) |
Sb | 0.0024 (2) | 0.0049 (2) | 0.0022 (2) | 0.0 | 0.0 | 0.0004 (2) |
Geometric parameters (Å, º) top
La—Sb | 3.3876 (7) | Sb—Sb | 2.964 (1) |
Fe,Co—Sb | 2.5392 (3) | Sb—Sb | 3.4257 (7) |
Sb—Sb | 2.907 (1) | | |
| | | |
Sb—Fe,Co—Sb | 95.16 (2) | Fe,Co—Sb—Fe,Co | 126.85 (2) |
Sb—Fe,Co—Sb | 84.83 (2) | | |
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.953 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0771 (4) Å | µ = 0.02 mm−1 |
V = 747.89 Å3 | T = 25 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
1362 measured reflections | k = 0→16 |
459 independent reflections | l = 0→16 |
348 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.041 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.049 | (Δ/σ)max < 0.001 |
wR(F2) = 0.036 | Δρmax = 0.40 e Å−3 |
S = 1.39 | Δρmin = −0.34 e Å−3 |
348 reflections | Extinction correction: B-C type I Gaussian isotropic |
11 parameters | Extinction coefficient: 1.8E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0066 (3) | .743 |
Fe | 0.25 | 0.25 | 0.25 | 0.0026 (1) | .686 |
Co | 0.25 | 0.25 | 0.25 | 0.0026 (1) | .314 |
Sb | 0.0 | 0.33674 (8) | 0.15996 (7) | 0.0032 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0066 (4) | 0.0066 (4) | 0.0066 (4) | 0.0 | 0.0 | 0.0 |
Fe | 0.00264 (14) | 0.00264 (14) | 0.00264 (14) | 0.00016 (15) | 0.00016 (15) | 0.00016 (15) |
Co | 0.00264 (14) | 0.00264 (14) | 0.00264 (14) | 0.00016 (15) | 0.00016 (15) | 0.00016 (15) |
Sb | 0.0025 (2) | 0.0049 (2) | 0.0021 (2) | 0.0 | 0.0 | 0.0004 (2) |
Geometric parameters (Å, º) top
La—Sb | 3.3839 (8) | Sb—Sb | 2.963 (1) |
Fe,Co—Sb | 2.5372 (3) | Sb—Sb | 3.4241 (7) |
Sb—Sb | 2.903 (1) | | |
| | | |
Sb—Fe,Co—Sb | 95.12 (2) | Fe,Co—Sb—Fe,Co | 126.86 (2) |
Sb—Fe,Co—Sb | 84.87 (2) | | |
Crystal data top
La.743Fe2.74Co1.26Sb12 | Dx = 7.955 Mg m−3 |
Mr = 1791.49 | Neutron radiation, λ = 0.8387 Å |
Cubic, Im3 | Cell parameters from 31 reflections |
Hall symbol: -I 2 2 3 | θ = 18.2–42.6° |
a = 9.0762 (12) Å | µ = 0.02 mm−1 |
V = 747.67 Å3 | T = 10 K |
Z = 2 | Sawn parallelepiped, silver |
F(000) = 20.63 | 3.5 × 2.5 × 2.5 mm |
Data collection top
Huber 4-circle, Crystal Logic Controller, Helium-3 detector, DEC Alpha
computer diffractometer | θmax = 50° |
Radial–scans | h = 0→16 |
1492 measured reflections | k = 0→16 |
472 independent reflections | l = 0→16 |
323 reflections with 0.0 | 3 standard reflections every 200 reflections |
Rint = 0.047 | intensity decay: none |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | w = (2Fo/σFo2)2 |
R[F2 > 2σ(F2)] = 0.037 | (Δ/σ)max < 0.001 |
wR(F2) = 0.029 | Δρmax = 0.72 e Å−3 |
S = 1.16 | Δρmin = −0.57 e Å−3 |
323 reflections | Extinction correction: B-C type I Gaussian isotropic |
11 parameters | Extinction coefficient: 3.1E-04 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
La | 0.0 | 0.0 | 0.0 | 0.0069 (3) | .743 |
Fe | 0.25 | 0.25 | 0.25 | 0.0026 (1) | .686 |
Co | 0.25 | 0.25 | 0.25 | 0.0026 (1) | .314 |
Sb | 0.0 | 0.33669 (7) | 0.15998 (6) | 0.0029 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
La | 0.0069 (3) | 0.0069 (3) | 0.0069 (3) | 0.0 | 0.0 | 0.0 |
Fe | 0.00263 (12) | 0.00263 (12) | 0.00263 (12) | −0.00010 (13) | −0.00010 (13) | −0.00010 (13) |
Co | 0.00263 (12) | 0.00263 (12) | 0.00263 (12) | −0.00010 (13) | −0.00010 (13) | −0.00010 (13) |
Sb | 0.00188 (19) | 0.0046 (2) | 0.00223 (19) | 0.0 | 0.0 | 0.00040 (19) |
Geometric parameters (Å, º) top
La—Sb | 3.3833 (8) | Sb—Sb | 2.964 (1) |
Fe,Co—Sb | 2.5368 (4) | Sb—Sb | 3.4237 (8) |
Sb—Sb | 2.904 (1) | | |
| | | |
Sb—Fe,Co—Sb | 95.12 (2) | Fe,Co—Sb—Fe,Co | 126.88 (2) |
Sb—Fe,Co—Sb | 84.87 (2) | | |