Buy article online - an online subscription or single-article purchase is required to access this article.
Ge2Bi2Te5 in the GeTe-Bi2Te3 pseudobinary system has two single-crystalline phases: a metastable phase with an NaCl-type structure and a stable phase with a nine-layer trigonal structure. In the metastable phase, the structure consists, in the hexagonal notation, of infinitely alternating stacks of Te and Ge/Bi layers at equal intervals along the c axis. On the other hand, in the stable phase those two layers are stacked alternately nine times to form an NaCl block. The blocks are then piled to construct a nine-layered trigonal structure with cubic close-packed stacking. Both ends of each block are covered with Te layers, contrary to the infinite alternation of Ge/Bi and Te layers in the structure of the metastable phase. The Ge/Bi layers in the metastable phase contain as much as 20 at. % vacancies; on the other hand, those in the stable phase are filled with atoms. These two crystalline phases in Ge2Bi2Te5 have identical atomic configurations to the two corresponding phases found in Ge2Sb2Te5.
Supporting information
Approximately 300 nm-thick Ge2Bi2Te5 thin film was deposited onto a 120 mm-diameter glass disc at room temperature by DC magnetron sputtering from stoichiometric GeTe-Bi2Te3 compound target in an Ar gas atmosphere set at about 0.2 Pa.
For all compounds, cell refinement: Rietan (Izumi, F. & Ikeda, T., 2000); data reduction: Rietan; program(s) used to solve structure: Rietan; program(s) used to refine structure: Rietan.
Crystal data top
Ge1.6Bi1.6Te4 | Dx = 6.98 Mg m−3 |
Mr = 960.83 | Synchrotron, radiation radiation, λ = 0.42182 Å |
Cubic, Fm3m | µ = 11.52 mm−1 |
a = 6.0932 (5) Å | T = 87 K |
V = 226.22 (3) Å3 | cylinder, 3.0 × 0.1 mm |
Z = 1 | Specimen preparation: Prepared at 300 K and 0.0002 kPa, cooled at 0 K min−1 |
Data collection top
Debye-Scherrer camera diffractometer | Specimen mounting: sealed quartz capillary tube |
Radiation source: synchrotron | Data collection mode: transmission |
Vertical focusing mirror + Si (111) double monochromator | Scan method: Stationary detector |
Refinement top
Refinement on Inet | Excluded region(s): none |
Rp = 0.013 | Profile function: pseudo-Voigt |
Rwp = 0.018 | 28 parameters |
Rexp = 0.028 | Weighting scheme based on measured s.u.'s |
RBragg = 0.005 | |
χ2 = 0.436 | Background function: Legendre polynomial |
7360 data points | Preferred orientation correction: March-Dollase function, axis (511) |
Crystal data top
Ge1.6Bi1.6Te4 | Z = 1 |
Mr = 960.83 | Synchrotron, radiation radiation, λ = 0.42182 Å |
Cubic, Fm3m | µ = 11.52 mm−1 |
a = 6.0932 (5) Å | T = 87 K |
V = 226.22 (3) Å3 | cylinder, 3.0 × 0.1 mm |
Data collection top
Debye-Scherrer camera diffractometer | Data collection mode: transmission |
Specimen mounting: sealed quartz capillary tube | Scan method: Stationary detector |
Refinement top
Rp = 0.013 | χ2 = 0.436 |
Rwp = 0.018 | 7360 data points |
Rexp = 0.028 | 28 parameters |
RBragg = 0.005 | |
Special details top
Experimental. Japan Synchrotron Radiation Research Institute (SPring-8) 1–1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679–5198 Japan |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Ge1 | 0.50000 | 0.50000 | 0.50000 | 0.0590 (18)* | 0.3970 (58) |
Bi1 | 0.50000 | 0.50000 | 0.50000 | 0.0590* | 0.3970 |
Te1 | 0.00000 | 0.00000 | 0.00000 | 0.0261 (14)* | |
Crystal data top
Ge1.6Bi1.6Te4 | Dx = 6.96 Mg m−3 |
Mr = 960.83 | Synchrotron, radiation radiation, λ = 0.42182 Å |
Cubic, Fm3m | µ = 11.51 mm−1 |
a = 6.1109 (9) Å | T = 293 K |
V = 228.20 (6) Å3 | cylinder, 3.0 × 0.1 mm |
Z = 1 | Specimen preparation: Prepared at 300 K and 0.0002 kPa, cooled at 0 K min−1 |
Data collection top
Debye-Scherrer camera diffractometer | Specimen mounting: sealed quartz capillary tube |
Radiation source: synchrotron | Data collection mode: transmission |
Vertical focusing mirror + Si (111) double monochromator | Scan method: Stationary detector |
Refinement top
Refinement on Inet | Excluded region(s): none |
Rp = 0.015 | Profile function: pseudo-Voigt |
Rwp = 0.024 | 27 parameters |
Rexp = 0.038 | Weighting scheme based on measured s.u.'s |
RBragg = 0.007 | |
χ2 = 0.384 | Background function: Legendre polynomial |
7360 data points | Preferred orientation correction: March-Dollase function, axis (100) |
Crystal data top
Ge1.6Bi1.6Te4 | Z = 1 |
Mr = 960.83 | Synchrotron, radiation radiation, λ = 0.42182 Å |
Cubic, Fm3m | µ = 11.51 mm−1 |
a = 6.1109 (9) Å | T = 293 K |
V = 228.20 (6) Å3 | cylinder, 3.0 × 0.1 mm |
Data collection top
Debye-Scherrer camera diffractometer | Data collection mode: transmission |
Specimen mounting: sealed quartz capillary tube | Scan method: Stationary detector |
Refinement top
Rp = 0.015 | χ2 = 0.384 |
Rwp = 0.024 | 7360 data points |
Rexp = 0.038 | 27 parameters |
RBragg = 0.007 | |
Special details top
Experimental. Japan Synchrotron Radiation Research Institute (SPring-8) 1–1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679–5198 Japan |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Ge1 | 0.50000 | 0.50000 | 0.50000 | 0.0316 (8)* | 0.3905 (23) |
Bi1 | 0.50000 | 0.50000 | 0.50000 | 0.03157* | 0.3905 |
Te1 | 0.00000 | 0.00000 | 0.00000 | 0.0191 (6)* | |
Crystal data top
Ge2Bi2Te5 | Dx = 7.28 Mg m−3 |
Mr = 1201.04 | Synchrotron, radiation radiation, λ = 0.42182 Å |
Trigonal, P3m1 | µ = 12.03 mm−1 |
a = 4.28072 (12) Å | T = 87 K |
c = 17.2651 (6) Å | cylinder, 3.0 × 0.1 mm |
V = 273.99 (1) Å3 | Specimen preparation: Prepared at 300 K and 0.0002 kPa, cooled at 0 K min−1 |
Z = 1 | |
Data collection top
Debye-Scherrer camera diffractometer | Specimen mounting: sealed quartz capillary tube |
Radiation source: synchrotron | Data collection mode: transmission |
Vertical focusing mirror + Si (111) double monochromator | Scan method: Stationary detector |
Refinement top
Refinement on Inet | Excluded region(s): none |
Rp = 0.018 | Profile function: pseudo-Voigt |
Rwp = 0.028 | 36 parameters |
Rexp = 0.038 | Weighting scheme based on measured s.u.'s |
RBragg = 0.016 | |
χ2 = 0.548 | Background function: Legendre polynomial |
7360 data points | Preferred orientation correction: March-Dollase function, axis (103) |
Crystal data top
Ge2Bi2Te5 | Z = 1 |
Mr = 1201.04 | Synchrotron, radiation radiation, λ = 0.42182 Å |
Trigonal, P3m1 | µ = 12.03 mm−1 |
a = 4.28072 (12) Å | T = 87 K |
c = 17.2651 (6) Å | cylinder, 3.0 × 0.1 mm |
V = 273.99 (1) Å3 | |
Data collection top
Debye-Scherrer camera diffractometer | Data collection mode: transmission |
Specimen mounting: sealed quartz capillary tube | Scan method: Stationary detector |
Refinement top
Rp = 0.018 | χ2 = 0.548 |
Rwp = 0.028 | 7360 data points |
Rexp = 0.038 | 36 parameters |
RBragg = 0.016 | |
Special details top
Experimental. Japan Synchrotron Radiation Research Institute (SPring-8) 1–1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679–5198 Japan |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Te1 | 0.00000 | 0.00000 | 0.00000 | 0.0019 (14)* | |
Ge2 | 0.66667 | 0.33333 | 0.1069 (3) | 0.0179 (10)* | 0.6379 (70) |
Bi2 | 0.66667 | 0.33333 | 0.10692 | 0.01786* | 0.3621 |
Te3 | 0.33333 | 0.66667 | 0.2031 (2) | 0.0076 (10)* | |
Ge4 | 0.00000 | 0.00000 | 0.32630 | 0.0168 (8)* | 0.3621 |
Bi4 | 0.00000 | 0.00000 | 0.32630 (17) | 0.01676* | 0.6379 |
Te5 | 0.66667 | 0.33333 | 0.4212 (2) | 0.0106 (11)* | |
Crystal data top
Ge2Bi2Te5 | Dx = 7.17 Mg m−3 |
Mr = 1201.04 | Synchrotron, radiation radiation, λ = 0.42206 Å |
Trigonal, P3m1 | µ = 11.85 mm−1 |
a = 4.30040 (13) Å | T = 293 K |
c = 17.3659 (6) Å | cylinder, 3.0 × 0.1 mm |
V = 278.13 (2) Å3 | Specimen preparation: Prepared at 300 K and 0.0002 kPa, cooled at 0 K min−1 |
Z = 1 | |
Data collection top
Debye-Scherrer camera diffractometer | Specimen mounting: sealed quartz capillary tube |
Radiation source: synchrotron | Data collection mode: transmission |
Vertical focusing mirror + Si (111) double monochromator | Scan method: Stationary detector |
Refinement top
Refinement on Inet | Excluded region(s): none |
Rp = 0.021 | Profile function: pseudo-Voigt |
Rwp = 0.035 | 36 parameters |
Rexp = 0.021 | Weighting scheme based on measured s.u.'s |
RBragg = 0.021 | |
χ2 = 2.993 | Background function: Legendre polynomial |
7360 data points | Preferred orientation correction: March-Dollase function, axis (001) |
Crystal data top
Ge2Bi2Te5 | Z = 1 |
Mr = 1201.04 | Synchrotron, radiation radiation, λ = 0.42206 Å |
Trigonal, P3m1 | µ = 11.85 mm−1 |
a = 4.30040 (13) Å | T = 293 K |
c = 17.3659 (6) Å | cylinder, 3.0 × 0.1 mm |
V = 278.13 (2) Å3 | |
Data collection top
Debye-Scherrer camera diffractometer | Data collection mode: transmission |
Specimen mounting: sealed quartz capillary tube | Scan method: Stationary detector |
Refinement top
Rp = 0.021 | χ2 = 2.993 |
Rwp = 0.035 | 7360 data points |
Rexp = 0.021 | 36 parameters |
RBragg = 0.021 | |
Special details top
Experimental. Japan Synchrotron Radiation Research Institute (SPring-8) 1–1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679–5198 Japan |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Te1 | 0.00000 | 0.00000 | 0.00000 | 0.015 (2)* | |
Ge2 | 0.66667 | 0.33333 | 0.1063 (4) | 0.0274 (13)* | 0.6440 (85) |
Bi2 | 0.66667 | 0.33333 | 0.10634 | 0.02744* | 0.3560 |
Te3 | 0.33333 | 0.66667 | 0.2042 (3) | 0.0143 (14)* | |
Ge4 | 0.00000 | 0.00000 | 0.32762 | 0.0263 (10)* | 0.3560 |
Bi4 | 0.00000 | 0.00000 | 0.3276 (2) | 0.02631* | 0.6440 |
Te5 | 0.66667 | 0.33333 | 0.4205 (3) | 0.0240 (17)* | |
Experimental details
| (metastable_87K) | (metastable_293K) | (stable_87K) | (stable_293K) |
Crystal data |
Chemical formula | Ge1.6Bi1.6Te4 | Ge1.6Bi1.6Te4 | Ge2Bi2Te5 | Ge2Bi2Te5 |
Mr | 960.83 | 960.83 | 1201.04 | 1201.04 |
Crystal system, space group | Cubic, Fm3m | Cubic, Fm3m | Trigonal, P3m1 | Trigonal, P3m1 |
Temperature (K) | 87 | 293 | 87 | 293 |
a, b, c (Å) | 6.0932 (5), 6.0932, 6.0932 | 6.1109 (9), 6.1109, 6.1109 | 4.28072 (12), 4.28072, 17.2651 (6) | 4.30040 (13), 4.30040, 17.3659 (6) |
α, β, γ (°) | 90, 90, 90 | 90, 90, 90 | 90, 90, 120 | 90, 90, 120 |
V (Å3) | 226.22 (3) | 228.20 (6) | 273.99 (1) | 278.13 (2) |
Z | 1 | 1 | 1 | 1 |
Radiation type | Synchrotron,, λ = 0.42182 Å | Synchrotron,, λ = 0.42182 Å | Synchrotron,, λ = 0.42182 Å | Synchrotron,, λ = 0.42206 Å |
µ (mm−1) | 11.52 | 11.51 | 12.03 | 11.85 |
Specimen shape, size (mm) | Cylinder, 3.0 × 0.1 | Cylinder, 3.0 × 0.1 | Cylinder, 3.0 × 0.1 | Cylinder, 3.0 × 0.1 |
|
Data collection |
Diffractometer | Debye-Scherrer camera diffractometer | Debye-Scherrer camera diffractometer | Debye-Scherrer camera diffractometer | Debye-Scherrer camera diffractometer |
Specimen mounting | Sealed quartz capillary tube | Sealed quartz capillary tube | Sealed quartz capillary tube | Sealed quartz capillary tube |
Data collection mode | Transmission | Transmission | Transmission | Transmission |
Scan method | Stationary detector | Stationary detector | Stationary detector | Stationary detector |
2θ values (°) | 2θfixed = ? | 2θfixed = ? | 2θfixed = ? | 2θfixed = ? |
|
Refinement |
R factors and goodness of fit | Rp = 0.013, Rwp = 0.018, Rexp = 0.028, RBragg = 0.005, χ2 = 0.436 | Rp = 0.015, Rwp = 0.024, Rexp = 0.038, RBragg = 0.007, χ2 = 0.384 | Rp = 0.018, Rwp = 0.028, Rexp = 0.038, RBragg = 0.016, χ2 = 0.548 | Rp = 0.021, Rwp = 0.035, Rexp = 0.021, RBragg = 0.021, χ2 = 2.993 |
No. of data points | 7360 | 7360 | 7360 | 7360 |
No. of parameters | 28 | 27 | 36 | 36 |
No. of restraints | ? | ? | ? | ? |
Subscribe to Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
The full text of this article is available to subscribers to the journal.
If you have already registered and are using a computer listed in your registration details, please email
support@iucr.org for assistance.