Vacancy-ordering effects in AlB2-type ErGe2 − x (0.4 < x ≤ 0.5)

Christensen, J.; Lidin, S.; Malaman, B.; Venturini, G.

doi:10.1107/S0108768108005119

Vacancy-ordering effects in AlB₂-type ErGe_{2 − x} (0.4 < x ≤ 0.5)

J. Christensen, S. Lidin, B. Malaman and G. Venturini

In the Er–Ge system, the compostion range ErGe₂ to Er₂Ge₃ has been investigated. Eight samples were produced by arc melting of the elements, and analyzed using X-ray powder diffraction. Nine crystal structures were found to be present in the samples. The structures are described as a homologous series and presented within the superspace formalism using the superspace group X2/m(α0γ)0s, X representing the centring vector (½, ½, 0, ½). In this description the modulation vector q = (αa* + γc*) is shown to be a direct measure of the Ge content as ErGe_2 − α (α falls in the range $1\over 3$ to ½). The large composition range is achieved by extended vacancy ordering in the planar 6³ net of Ge with subsequent relaxation.

Keywords: modulation; rare-earth germanides; vacancy ordering.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768108005119/ck5030sup1.cif Contains datablocks global, I, II, III, IV, V, VI, VII, VIII, IX
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030Isup2.rtv Contains datablock I
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030IIsup3.rtv Contains datablock II
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030IIIsup4.rtv Contains datablock III
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030IVsup5.rtv Contains datablock IV
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030Vsup6.rtv Contains datablock V
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030VIsup7.rtv Contains datablock VI
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030VIIsup8.rtv Contains datablock VII
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030VIIIsup9.rtv Contains datablock VIII
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768108005119/ck5030IXsup10.rtv Contains datablock IX

Computing details top

For all compounds, cell refinement: (Jana2000; Petricek and Dusek, 2000); program(s) used to refine structure: (Jana2000; Petricek and Dusek, 2000); software used to prepare material for publication: (Jana2000; Petricek and Dusek, 2000).

Figures top

(I) top

Crystal data top

Er₂Ge_3.188	Z = 2
M_r = 565.9	F(000) = 476
Monoclinic, X2/m(α0γ)0s†	D_x = 8.664 Mg m⁻³
q = 0.40577(17)a* + 0.2205(3)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9208 (2) Å	µ = 91.77 mm⁻¹
b = 6.7547 (4) Å	T = 295 K
c = 4.0945 (2) Å	gray metallic
β = 89.811 (4)°	cylinder, ? × ? × ? mm
V = 108.44 (1) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 13.008°, 2θ_max = 119.994°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	51 parameters
R_p = 0.032	0 restraints
R_wp = 0.045	1 constraint
R_exp = 0.011	Weighting scheme based on measured s.u.'s
R(F) = 0.059	(Δ/σ)_max = 0.050
χ² = 15.920	Background function: 10 Legendre polynoms
6403 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge_3.188	β = 89.811 (4)°
M_r = 565.9	V = 108.44 (1) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.40577(17)a* + 0.2205(3)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9208 (2) Å	µ = 91.77 mm⁻¹
b = 6.7547 (4) Å	T = 295 K
c = 4.0945 (2) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 13.008°, 2θ_max = 119.994°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.032	χ² = 15.920
R_wp = 0.045	6403 data points
R_exp = 0.011	51 parameters
R(F) = 0.059	0 restraints

Special details top

Refinement. Impurities present are ErGe1.83 and Er2O3 Parameters for these were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ge	0.5	0.180 (3)	0.5	0.0149 (19)*
Er	0	0	0	0.0069 (11)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.58 (4)	2.46 (4)	2.66 (5)
Ge—Geⁱⁱ	2.55 (4)	2.34 (3)	2.65 (3)
Ge—Geⁱⁱⁱ	2.55 (4)	2.32 (3)	2.65 (3)
Ge—Er	3.08 (2)	2.95 (2)	3.44 (3)
Ge—Er^iv	3.06 (2)	2.88 (3)	3.55 (3)
Ge—Er^v	3.06 (2)	2.88 (2)	3.55 (3)
Ge—Er^vi	3.08 (2)	2.95 (2)	3.44 (3)
Ge—Er^vii	3.03 (3)	2.78 (3)	3.18 (6)
Ge—Er^viii	3.03 (3)	2.78 (3)	3.18 (6)

Symmetry codes: (i) −x₁+1, −x₂, −x₃+1, −x₄; (ii) −x₁+1/2, −x₂+1/2, −x₃+1, −x₁/2; (iii) −x₁+3/2, −x₂+1/2, −x₃+1, −x₁/2; (iv) x₁, x₂, x₃+1, x₄; (v) x₁+1, x₂, x₃, x₄; (vi) x₁+1, x₂, x₃+1, x₄; (vii) x₁+1/2, x₂+1/2, x₃, x₁/2; (viii) x₁+1/2, x₂+1/2, x₃+1, x₁/2.

(II) top

Crystal data top

Er₂Ge_3.188	Z = 2
M_r = 565.94	F(000) = 476
Monoclinic, X2/m(α0γ)0s†	D_x = 8.666 Mg m⁻³
q = 0.40612(16)a* + 0.2206(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9206 (2) Å	µ = 91.79 mm⁻¹
b = 6.7543 (4) Å	T = 295 K
c = 4.09383 (19) Å	gray-metallic
β = 89.813 (4)°	cylinder, ? × ? × ? mm
V = 108.41 (1) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 13.008°, 2θ_max = 119.994°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	51 parameters
R_p = 0.031	0 restraints
R_wp = 0.044	1 constraint
R_exp = 0.011	Weighting scheme based on measured s.u.'s
R(F) = 0.054	(Δ/σ)_max = 0.050
χ² = 14.823	Background function: 10 Legendre polynoms
6403 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge_3.188	β = 89.813 (4)°
M_r = 565.94	V = 108.41 (1) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.40612(16)a* + 0.2206(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9206 (2) Å	µ = 91.79 mm⁻¹
b = 6.7543 (4) Å	T = 295 K
c = 4.09383 (19) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 13.008°, 2θ_max = 119.994°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.031	χ² = 14.823
R_wp = 0.044	6403 data points
R_exp = 0.011	51 parameters
R(F) = 0.054	0 restraints

Special details top

Refinement. Impurities present are ErGe1.83 and Er2O3 Parameters for these were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ge	0.5	0.181 (2)	0.5	0.0122 (18)*
Er	0	0	0	0.0066 (10)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.59 (4)	2.46 (4)	2.67 (5)
Ge—Geⁱⁱ	2.56 (3)	2.36 (3)	2.67 (3)
Ge—Geⁱⁱⁱ	2.56 (3)	2.34 (3)	2.67 (3)
Ge—Er	3.08 (2)	2.93 (2)	3.45 (2)
Ge—Er^iv	3.06 (2)	2.86 (2)	3.57 (2)
Ge—Er^v	3.06 (2)	2.86 (2)	3.57 (2)
Ge—Er^vi	3.09 (2)	2.93 (2)	3.45 (2)
Ge—Er^vii	3.03 (3)	2.79 (3)	3.16 (5)
Ge—Er^viii	3.03 (3)	2.78 (3)	3.16 (5)

(III) top

Crystal data top

Er₂Ge_3.186	Z = 2
M_r = 565.79	F(000) = 476
Monoclinic, X2/m(α0γ)0s†	D_x = 8.665 Mg m⁻³
q = 0.40712(13)a* + 0.22091(19)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.92030 (18) Å	µ = 91.79 mm⁻¹
b = 6.7532 (3) Å	T = 295 K
c = 4.09406 (16) Å	gray-metallic
β = 89.813 (3)°	cylinder, ? × ? × ? mm
V = 108.39 (1) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 13.008°, 2θ_max = 119.994°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	51 parameters
R_p = 0.031	0 restraints
R_wp = 0.045	1 constraint
R_exp = 0.012	Weighting scheme based on measured s.u.'s
R(F) = 0.048	(Δ/σ)_max = 0.047
χ² = 15.054	Background function: 10 Legendre polynoms
6403 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge_3.186	β = 89.813 (3)°
M_r = 565.79	V = 108.39 (1) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.40712(13)a* + 0.22091(19)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.92030 (18) Å	µ = 91.79 mm⁻¹
b = 6.7532 (3) Å	T = 295 K
c = 4.09406 (16) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 13.008°, 2θ_max = 119.994°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.031	χ² = 15.054
R_wp = 0.045	6403 data points
R_exp = 0.012	51 parameters
R(F) = 0.048	0 restraints

Special details top

Refinement. Impurities present are ErGe1.83 and Er2O3 Parameters for these were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ge	0.5	0.181 (2)	0.5	0.0151 (17)*
Er	0	0	0	0.0080 (10)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.58 (3)	2.44 (4)	2.67 (4)
Ge—Geⁱⁱ	2.56 (3)	2.33 (2)	2.65 (2)
Ge—Geⁱⁱⁱ	2.55 (3)	2.31 (2)	2.65 (2)
Ge—Er	3.080 (19)	2.93 (2)	3.44 (2)
Ge—Er^iv	3.054 (18)	2.88 (2)	3.54 (2)
Ge—Er^v	3.057 (18)	2.88 (2)	3.54 (2)
Ge—Er^vi	3.082 (19)	2.93 (2)	3.44 (2)
Ge—Er^vii	3.03 (3)	2.80 (2)	3.17 (4)
Ge—Er^viii	3.03 (3)	2.80 (2)	3.17 (4)

(IV) top

Crystal data top

Er₂Ge_3.182	Z = 2
M_r = 565.50	F(000) = 476
Monoclinic, X2/m(α0γ)0s†	D_x = 8.664 Mg m⁻³
q = 0.40890(17)a* + 0.2214(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9198 (2) Å	µ = 91.79 mm⁻¹
b = 6.7518 (4) Å	T = 295 K
c = 4.0941 (2) Å	gray-metallic
β = 89.813 (4)°	cylinder, ? × ? × ? mm
V = 108.35 (1) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	51 parameters
R_p = 0.034	0 restraints
R_wp = 0.048	1 constraint
R_exp = 0.012	Weighting scheme based on measured s.u.'s
R(F) = 0.063	(Δ/σ)_max = 0.416
χ² = 16.080	Background function: 10 Legendre polynoms
7270 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge_3.182	β = 89.813 (4)°
M_r = 565.50	V = 108.35 (1) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.40890(17)a* + 0.2214(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9198 (2) Å	µ = 91.79 mm⁻¹
b = 6.7518 (4) Å	T = 295 K
c = 4.0941 (2) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.034	7270 data points
R_wp = 0.048	51 parameters
R_exp = 0.012	0 restraints
R(F) = 0.063	(Δ/σ)_max = 0.416
χ² = 16.080

Special details top

Refinement. Impurities present are ErGe1.83 and Er2O3 Parameters for these were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ge	0.5	0.182 (3)	0.5	0.015 (2)*
Er	0	0	0	0.0094 (13)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.60 (4)	2.45 (4)	2.69 (5)
Ge—Geⁱⁱ	2.55 (4)	2.32 (3)	2.65 (3)
Ge—Geⁱⁱⁱ	2.56 (4)	2.32 (3)	2.65 (3)
Ge—Er	3.08 (2)	2.93 (2)	3.45 (3)
Ge—Er^iv	3.06 (2)	2.88 (3)	3.54 (3)
Ge—Er^v	3.06 (2)	2.88 (3)	3.54 (3)
Ge—Er^vi	3.08 (2)	2.93 (2)	3.45 (3)
Ge—Er^vii	3.03 (3)	2.80 (3)	3.16 (5)
Ge—Er^viii	3.03 (3)	2.80 (3)	3.16 (5)

(V) top

Crystal data top

Er₂Ge_3.171	Z = 2
M_r = 564.70	F(000) = 476
Monoclinic, X2/m(α0γ)0s†	D_x = 8.662 Mg m⁻³
q = 0.41484(17)a* + 0.2236(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9183 (2) Å	µ = 91.83 mm⁻¹
b = 6.7475 (4) Å	T = 295 K
c = 4.0932 (2) Å	gray-metallic
β = 89.813 (4)°	cylinder, ? × ? × ? mm
V = 108.22 (1) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	41 parameters
R_p = 0.036	0 restraints
R_wp = 0.051	1 constraint
R_exp = 0.012	Weighting scheme based on measured s.u.'s
R(F) = 0.062	(Δ/σ)_max = 0.092
χ² = 17.140	Background function: 10 Legendre polynoms
7270 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge_3.171	β = 89.813 (4)°
M_r = 564.70	V = 108.22 (1) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.41484(17)a* + 0.2236(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9183 (2) Å	µ = 91.83 mm⁻¹
b = 6.7475 (4) Å	T = 295 K
c = 4.0932 (2) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.036	χ² = 17.140
R_wp = 0.051	7270 data points
R_exp = 0.012	41 parameters
R(F) = 0.062	0 restraints

Special details top

Refinement. Impurity present is Er2O3 Parameters for this were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ge	0.5	0.178 (3)	0.5	0.016 (2)*
Er	0	0	0	0.0098 (13)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.59 (4)	2.42 (4)	2.70 (5)
Ge—Geⁱⁱ	2.55 (3)	2.33 (3)	2.62 (3)
Ge—Geⁱⁱⁱ	2.55 (3)	2.29 (3)	2.62 (3)
Ge—Er	3.08 (2)	2.94 (2)	3.41 (2)
Ge—Er^iv	3.05 (2)	2.90 (2)	3.50 (2)
Ge—Er^v	3.05 (2)	2.90 (2)	3.50 (2)
Ge—Er^vi	3.08 (2)	2.94 (2)	3.41 (2)
Ge—Er^vii	3.03 (3)	2.83 (3)	3.17 (5)
Ge—Er^viii	3.03 (3)	2.83 (3)	3.17 (5)

(VI) top

Crystal data top

Er₂Ge_3.14	Z = 2
M_r = 562.45	F(000) = 746
Monoclinic, X2/m(α0γ)0s†	D_x = 8.654 Mg m⁻³
q = 0.42980(16)a* + 0.2278(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9142 (2) Å	µ = 91.87 mm⁻¹
b = 6.7363 (4) Å	T = 295 K
c = 4.0917 (2) Å	gray-metallic
β = 89.810 (4)°	cylinder, ? × ? × ? mm
V = 107.89 (1) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	42 parameters
R_p = 0.035	0 restraints
R_wp = 0.051	1 constraint
R_exp = 0.012	Weighting scheme based on measured s.u.'s
R(F) = 0.062	(Δ/σ)_max = 0.050
χ² = 17.223	Background function: 10 Legendre polynoms
7270 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge_3.14	β = 89.810 (4)°
M_r = 562.45	V = 107.89 (1) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.42980(16)a* + 0.2278(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9142 (2) Å	µ = 91.87 mm⁻¹
b = 6.7363 (4) Å	T = 295 K
c = 4.0917 (2) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.035	χ² = 17.223
R_wp = 0.051	7270 data points
R_exp = 0.012	42 parameters
R(F) = 0.062	0 restraints

Special details top

Refinement. Impurity present is Er2O3. Parameters for this were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ge	0.5	0.176 (4)	0.5	0.015 (2)*
Er	0	0	0	0.0079 (14)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.58 (4)	2.39 (4)	2.70 (5)
Ge—Geⁱⁱ	2.55 (4)	2.36 (3)	2.63 (3)
Ge—Geⁱⁱⁱ	2.55 (4)	2.35 (3)	2.63 (3)
Ge—Er	3.07 (2)	2.92 (3)	3.41 (3)
Ge—Er^iv	3.04 (2)	2.89 (2)	3.48 (3)
Ge—Er^v	3.05 (2)	2.89 (2)	3.48 (3)
Ge—Er^vi	3.08 (2)	2.92 (3)	3.41 (3)
Ge—Er^vii	3.03 (3)	2.84 (3)	3.17 (6)
Ge—Er^viii	3.03 (3)	2.84 (3)	3.17 (6)

(VII) top

Crystal data top

Er₂Ge_3.125	Z = 2
M_r = 561.36	F(000) = 476
Monoclinic, X2/m(α0γ)0s†	D_x = 8.653 Mg m⁻³
q = 0.43766(14)a* + 0.23005(19)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9117 (2) Å	µ = 91.92 mm⁻¹
b = 6.7296 (3) Å	T = 295 K
c = 4.09129 (19) Å	gray-metallic
β = 89.805 (4)°	cylinder, ? × ? × ? mm
V = 107.70 (1) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	37 parameters
R_p = 0.034	0 restraints
R_wp = 0.048	1 constraint
R_exp = 0.012	Weighting scheme based on measured s.u.'s
R(F) = 0.062	(Δ/σ)_max = 0.046
χ² = 15.761	Background function: 10 Legendre polynoms
7270 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge_3.125	β = 89.805 (4)°
M_r = 561.36	V = 107.70 (1) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.43766(14)a* + 0.23005(19)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9117 (2) Å	µ = 91.92 mm⁻¹
b = 6.7296 (3) Å	T = 295 K
c = 4.09129 (19) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.034	χ² = 15.761
R_wp = 0.048	7270 data points
R_exp = 0.012	37 parameters
R(F) = 0.062	0 restraints

Special details top

Refinement. Impurity present is Er2O3. Parameters for this were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ge	0.5	0.170 (3)	0.5	0.0172 (19)*
Er	0	0	0	0.0109 (12)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.51 (6)	2.20 (6)	2.70 (7)
Ge—Geⁱⁱ	2.53 (5)	1.47 (5)	2.63 (5)
Ge—Geⁱⁱⁱ	2.53 (5)	1.47 (5)	2.63 (5)
Ge—Er	3.06 (3)	2.93 (4)	3.32 (3)
Ge—Er^iv	3.03 (3)	2.88 (3)	3.43 (3)
Ge—Er^v	3.03 (3)	2.88 (3)	3.43 (3)
Ge—Er^vi	3.06 (3)	2.93 (4)	3.32 (3)
Ge—Er^vii	3.05 (4)	2.87 (3)	3.20 (8)
Ge—Er^viii	3.05 (4)	2.87 (3)	3.20 (8)

(VIII) top

Crystal data top

Er₂Ge_3.122	Z = 2
M_r = 561.15	F(000) = 476
Monoclinic, X2/m(α0γ)0s†	D_x = 8.651 Mg m⁻³
q = 0.43886(17)a* + 0.2302(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9113 (3) Å	µ = 91.92 mm⁻¹
b = 6.7290 (5) Å	T = 295 K
c = 4.0912 (2) Å	gray-metallic
β = 89.805 (5)°	cylinder, ? × ? × ? mm
V = 107.67 (2) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	36 parameters
R_p = 0.033	0 restraints
R_wp = 0.046	8 constraints
R_exp = 0.012	Weighting scheme based on measured s.u.'s
R(F) = 0.061	(Δ/σ)_max = 0.049
χ² = 14.364	Background function: 10 Legendre polynoms
7270 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge_3.122	β = 89.805 (5)°
M_r = 561.15	V = 107.67 (2) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.43886(17)a* + 0.2302(2)c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.9113 (3) Å	µ = 91.92 mm⁻¹
b = 6.7290 (5) Å	T = 295 K
c = 4.0912 (2) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.033	χ² = 14.364
R_wp = 0.046	7270 data points
R_exp = 0.012	36 parameters
R(F) = 0.061	0 restraints

Special details top

Refinement. Second phase present is Er2Ge3. Parameters for this were refined. Impurity present is Er2O3 Parameters for this were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ge	0.5	0.167 (3)	0.5	0.0139 (16)*
Er	0	0	0	0.0094 (9)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.51 (6)	2.18 (6)	2.72 (7)
Ge—Geⁱⁱ	2.53 (5)	1.50 (5)	2.63 (4)
Ge—Geⁱⁱⁱ	2.53 (5)	1.50 (5)	2.63 (4)
Ge—Er	3.06 (3)	2.88 (4)	3.36 (3)
Ge—Er^iv	3.03 (3)	2.86 (3)	3.40 (4)
Ge—Er^v	3.03 (3)	2.86 (3)	3.40 (4)
Ge—Er^vi	3.06 (3)	2.88 (4)	3.36 (3)
Ge—Er^vii	3.05 (4)	2.91 (4)	3.20 (8)
Ge—Er^viii	3.06 (4)	2.91 (4)	3.20 (8)

(IX) top

Crystal data top

Er₂Ge₃	Z = 2
M_r = 552.29	F(000) = 476
Monoclinic, X2/m(α0γ)0s†	D_x = 8.643 Mg m⁻³
q = 0.50000a* + 0.25000c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.8901 (10) Å	µ = 92.35 mm⁻¹
b = 6.6544 (11) Å	T = 295 K
c = 4.0980 (8) Å	gray-metallic
β = 89.74 (2)°	cylinder, ? × ? × ? mm
V = 106.08 (2) Å³

Data collection top

PANalytical X'pert PRO diffractometer	Scan method: continuous
Radiation source: sealed tube	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
None monochromator	T_min = ?, T_max = ?
Specimen mounting: capillary	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Data collection mode: transmission

Refinement top

Refinement on F²	36 parameters
R_p = 0.033	0 restraints
R_wp = 0.046	8 constraints
R_exp = 0.012	Weighting scheme based on measured s.u.'s
R(F) = 0.061	(Δ/σ)_max = 0.049
χ² = 14.364	Background function: 10 Legendre polynoms
7270 data points	Preferred orientation correction: none
Profile function: Pseudo-Voigt

Crystal data top

Er₂Ge₃	β = 89.74 (2)°
M_r = 552.29	V = 106.08 (2) Å³
Monoclinic, X2/m(α0γ)0s†	Z = 2
q = 0.50000a* + 0.25000c*	Cu Kα radiation, λ = 1.54178 Å
a = 3.8901 (10) Å	µ = 92.35 mm⁻¹
b = 6.6544 (11) Å	T = 295 K
c = 4.0980 (8) Å	cylinder, ? × ? × ? mm

Data collection top

PANalytical X'pert PRO diffractometer	Absorption correction: empirical (using intensity measurements) (Jana2000; Petricek, Dusek & Palatinus, 2000)
Specimen mounting: capillary	T_min = ?, T_max = ?
Data collection mode: transmission	2θ_min = 8.517°, 2θ_max = 129.992°, 2θ_step = 0.017°
Scan method: continuous

Refinement top

R_p = 0.033	χ² = 14.364
R_wp = 0.046	7270 data points
R_exp = 0.012	36 parameters
R(F) = 0.061	0 restraints

Special details top

Refinement. Presented phase is a minority phase. The main phase is Er2Ge3.122 Impurity present is Er2O3 Parameters for this were not refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Geb	0.5	0.166775	0.5	0.0139 (16)*
Erb	0	0	0	0.0094 (9)*

Bond lengths (Å) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.51 (6)	2.18 (6)	2.72 (7)
Ge—Geⁱⁱ	2.53 (5)	1.50 (5)	2.63 (4)
Ge—Geⁱⁱⁱ	2.53 (5)	1.50 (5)	2.63 (4)
Ge—Er	3.06 (3)	2.88 (4)	3.36 (3)
Ge—Er^iv	3.03 (3)	2.86 (3)	3.40 (4)
Ge—Er^v	3.03 (3)	2.86 (3)	3.40 (4)
Ge—Er^vi	3.06 (3)	2.88 (4)	3.36 (3)
Ge—Er^vii	3.05 (4)	2.91 (4)	3.20 (8)
Ge—Er^viii	3.06 (4)	2.91 (4)	3.20 (8)

Experimental details

	(I)	(II)	(III)	(IV)
Crystal data
Chemical formula	Er₂Ge_3.188	Er₂Ge_3.188	Er₂Ge_3.186	Er₂Ge_3.182
M_r	565.9	565.94	565.79	565.50
Crystal system, space group	Monoclinic, X2/m(α0γ)0s†	Monoclinic, X2/m(α0γ)0s‡	Monoclinic, X2/m(α0γ)0s§	Monoclinic, X2/m(α0γ)0s††
Temperature (K)	295	295	295	295
Wave vectors	q = 0.40577(17)a* + 0.2205(3)c*	q = 0.40612(16)a* + 0.2206(2)c*	q = 0.40712(13)a* + 0.22091(19)c*	q = 0.40890(17)a* + 0.2214(2)c*
a, b, c (Å)	3.9208 (2), 6.7547 (4), 4.0945 (2)	3.9206 (2), 6.7543 (4), 4.09383 (19)	3.92030 (18), 6.7532 (3), 4.09406 (16)	3.9198 (2), 6.7518 (4), 4.0941 (2)
β (°)	89.811 (4)	89.813 (4)	89.813 (3)	89.813 (4)
V (Å³)	108.44 (1)	108.41 (1)	108.39 (1)	108.35 (1)
Z	2	2	2	2
Radiation type	Cu Kα, λ = 1.54178 Å	Cu Kα, λ = 1.54178 Å	Cu Kα, λ = 1.54178 Å	Cu Kα, λ = 1.54178 Å
µ (mm⁻¹)	91.77	91.79	91.79	91.79
Specimen shape, size (mm)	Cylinder, ? × ? × ?	Cylinder, ? × ? × ?	Cylinder, ? × ? × ?	Cylinder, ? × ? × ?

Data collection
Diffractometer	PANalytical X'pert PRO diffractometer	PANalytical X'pert PRO diffractometer	PANalytical X'pert PRO diffractometer	PANalytical X'pert PRO diffractometer
Specimen mounting	Capillary	Capillary	Capillary	Capillary
Data collection mode	Transmission	Transmission	Transmission	Transmission
Scan method	Continuous	Continuous	Continuous	Continuous
Absorption correction	Empirical (Jana2000; Petricek, Dusek & Palatinus, 2000)	–	–	–
2θ values (°)	2θ_min = 13.008 2θ_max = 119.994 2θ_step = 0.017	2θ_min = 13.008 2θ_max = 119.994 2θ_step = 0.017	2θ_min = 13.008 2θ_max = 119.994 2θ_step = 0.017	2θ_min = 8.517 2θ_max = 129.992 2θ_step = 0.017

Refinement
R factors and goodness of fit	R_p = 0.032, R_wp = 0.045, R_exp = 0.011, R(F) = 0.059, χ² = 15.920	R_p = 0.031, R_wp = 0.044, R_exp = 0.011, R(F) = 0.054, χ² = 14.823	R_p = 0.031, R_wp = 0.045, R_exp = 0.012, R(F) = 0.048, χ² = 15.054	R_p = 0.034, R_wp = 0.048, R_exp = 0.012, R(F) = 0.063, χ² = 16.080
No. of data points	6403	6403	6403	7270
No. of parameters	51	51	51	51
(Δ/σ)_max	0.050	0.050	0.047	0.416

	(V)	(VI)	(VII)	(VIII)
Crystal data
Chemical formula	Er₂Ge_3.171	Er₂Ge_3.14	Er₂Ge_3.125	Er₂Ge_3.122
M_r	564.70	562.45	561.36	561.15
Crystal system, space group	Monoclinic, X2/m(α0γ)0s‡‡	Monoclinic, X2/m(α0γ)0s§§	Monoclinic, X2/m(α0γ)0s†††	Monoclinic, X2/m(α0γ)0s‡‡‡
Temperature (K)	295	295	295	295
Wave vectors	q = 0.41484(17)a* + 0.2236(2)c*	q = 0.42980(16)a* + 0.2278(2)c*	q = 0.43766(14)a* + 0.23005(19)c*	q = 0.43886(17)a* + 0.2302(2)c*
a, b, c (Å)	3.9183 (2), 6.7475 (4), 4.0932 (2)	3.9142 (2), 6.7363 (4), 4.0917 (2)	3.9117 (2), 6.7296 (3), 4.09129 (19)	3.9113 (3), 6.7290 (5), 4.0912 (2)
β (°)	89.813 (4)	89.810 (4)	89.805 (4)	89.805 (5)
V (Å³)	108.22 (1)	107.89 (1)	107.70 (1)	107.67 (2)
Z	2	2	2	2
Radiation type	Cu Kα, λ = 1.54178 Å	Cu Kα, λ = 1.54178 Å	Cu Kα, λ = 1.54178 Å	Cu Kα, λ = 1.54178 Å
µ (mm⁻¹)	91.83	91.87	91.92	91.92
Specimen shape, size (mm)	Cylinder, ? × ? × ?	Cylinder, ? × ? × ?	Cylinder, ? × ? × ?	Cylinder, ? × ? × ?

Data collection
Diffractometer	PANalytical X'pert PRO diffractometer	PANalytical X'pert PRO diffractometer	PANalytical X'pert PRO diffractometer	PANalytical X'pert PRO diffractometer
Specimen mounting	Capillary	Capillary	Capillary	Capillary
Data collection mode	Transmission	Transmission	Transmission	Transmission
Scan method	Continuous	Continuous	Continuous	Continuous
Absorption correction	–	–	–	–
2θ values (°)	2θ_min = 8.517 2θ_max = 129.992 2θ_step = 0.017	2θ_min = 8.517 2θ_max = 129.992 2θ_step = 0.017	2θ_min = 8.517 2θ_max = 129.992 2θ_step = 0.017	2θ_min = 8.517 2θ_max = 129.992 2θ_step = 0.017

Refinement
R factors and goodness of fit	R_p = 0.036, R_wp = 0.051, R_exp = 0.012, R(F) = 0.062, χ² = 17.140	R_p = 0.035, R_wp = 0.051, R_exp = 0.012, R(F) = 0.062, χ² = 17.223	R_p = 0.034, R_wp = 0.048, R_exp = 0.012, R(F) = 0.062, χ² = 15.761	R_p = 0.033, R_wp = 0.046, R_exp = 0.012, R(F) = 0.061, χ² = 14.364
No. of data points	7270	7270	7270	7270
No. of parameters	41	42	37	36
(Δ/σ)_max	0.092	0.050	0.046	0.049

	(IX)
Crystal data
Chemical formula	Er₂Ge₃
M_r	552.29
Crystal system, space group	Monoclinic, X2/m(α0γ)0s§§§
Temperature (K)	295
Wave vectors	q = 0.50000a* + 0.25000c*
a, b, c (Å)	3.8901 (10), 6.6544 (11), 4.0980 (8)
β (°)	89.74 (2)
V (Å³)	106.08 (2)
Z	2
Radiation type	Cu Kα, λ = 1.54178 Å
µ (mm⁻¹)	92.35
Specimen shape, size (mm)	Cylinder, ? × ? × ?

Data collection
Diffractometer	PANalytical X'pert PRO diffractometer
Specimen mounting	Capillary
Data collection mode	Transmission
Scan method	Continuous
Absorption correction	–
2θ values (°)	2θ_min = 8.517 2θ_max = 129.992 2θ_step = 0.017

Refinement
R factors and goodness of fit	R_p = 0.033, R_wp = 0.046, R_exp = 0.012, R(F) = 0.061, χ² = 14.364
No. of data points	7270
No. of parameters	36
(Δ/σ)_max	0.049

† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

‡ Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

§ Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

†† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

‡‡ Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

§§ Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

††† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

‡‡‡ Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

§§§ Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, 1/2−x₄; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, 1/2+x₄; (5) 1/2+x₁, 1/2+x₂, x₃, 1/2+x₄; (6) 1/2−x₁, 1/2+x₂, −x₃, −x₄; (7) 1/2−x₁, 1/2−x₂, −x₃, 1/2−x₄; (8) 1/2+x₁, 1/2−x₂, x₃, x₄.

Computer programs: (Jana2000; Petricek and Dusek, 2000).

Selected bond lengths (Å) for (I) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.58 (4)	2.46 (4)	2.66 (5)
Ge—Geⁱⁱ	2.55 (4)	2.34 (3)	2.65 (3)
Ge—Geⁱⁱⁱ	2.55 (4)	2.32 (3)	2.65 (3)
Ge—Er	3.08 (2)	2.95 (2)	3.44 (3)
Ge—Er^iv	3.06 (2)	2.88 (3)	3.55 (3)
Ge—Er^v	3.06 (2)	2.88 (2)	3.55 (3)
Ge—Er^vi	3.08 (2)	2.95 (2)	3.44 (3)
Ge—Er^vii	3.03 (3)	2.78 (3)	3.18 (6)
Ge—Er^viii	3.03 (3)	2.78 (3)	3.18 (6)

Selected bond lengths (Å) for (II) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.59 (4)	2.46 (4)	2.67 (5)
Ge—Geⁱⁱ	2.56 (3)	2.36 (3)	2.67 (3)
Ge—Geⁱⁱⁱ	2.56 (3)	2.34 (3)	2.67 (3)
Ge—Er	3.08 (2)	2.93 (2)	3.45 (2)
Ge—Er^iv	3.06 (2)	2.86 (2)	3.57 (2)
Ge—Er^v	3.06 (2)	2.86 (2)	3.57 (2)
Ge—Er^vi	3.09 (2)	2.93 (2)	3.45 (2)
Ge—Er^vii	3.03 (3)	2.79 (3)	3.16 (5)
Ge—Er^viii	3.03 (3)	2.78 (3)	3.16 (5)

Selected bond lengths (Å) for (III) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.58 (3)	2.44 (4)	2.67 (4)
Ge—Geⁱⁱ	2.56 (3)	2.33 (2)	2.65 (2)
Ge—Geⁱⁱⁱ	2.55 (3)	2.31 (2)	2.65 (2)
Ge—Er	3.080 (19)	2.93 (2)	3.44 (2)
Ge—Er^iv	3.054 (18)	2.88 (2)	3.54 (2)
Ge—Er^v	3.057 (18)	2.88 (2)	3.54 (2)
Ge—Er^vi	3.082 (19)	2.93 (2)	3.44 (2)
Ge—Er^vii	3.03 (3)	2.80 (2)	3.17 (4)
Ge—Er^viii	3.03 (3)	2.80 (2)	3.17 (4)

Selected bond lengths (Å) for (IV) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.60 (4)	2.45 (4)	2.69 (5)
Ge—Geⁱⁱ	2.55 (4)	2.32 (3)	2.65 (3)
Ge—Geⁱⁱⁱ	2.56 (4)	2.32 (3)	2.65 (3)
Ge—Er	3.08 (2)	2.93 (2)	3.45 (3)
Ge—Er^iv	3.06 (2)	2.88 (3)	3.54 (3)
Ge—Er^v	3.06 (2)	2.88 (3)	3.54 (3)
Ge—Er^vi	3.08 (2)	2.93 (2)	3.45 (3)
Ge—Er^vii	3.03 (3)	2.80 (3)	3.16 (5)
Ge—Er^viii	3.03 (3)	2.80 (3)	3.16 (5)

Selected bond lengths (Å) for (V) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.59 (4)	2.42 (4)	2.70 (5)
Ge—Geⁱⁱ	2.55 (3)	2.33 (3)	2.62 (3)
Ge—Geⁱⁱⁱ	2.55 (3)	2.29 (3)	2.62 (3)
Ge—Er	3.08 (2)	2.94 (2)	3.41 (2)
Ge—Er^iv	3.05 (2)	2.90 (2)	3.50 (2)
Ge—Er^v	3.05 (2)	2.90 (2)	3.50 (2)
Ge—Er^vi	3.08 (2)	2.94 (2)	3.41 (2)
Ge—Er^vii	3.03 (3)	2.83 (3)	3.17 (5)
Ge—Er^viii	3.03 (3)	2.83 (3)	3.17 (5)

Selected bond lengths (Å) for (VI) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.58 (4)	2.39 (4)	2.70 (5)
Ge—Geⁱⁱ	2.55 (4)	2.36 (3)	2.63 (3)
Ge—Geⁱⁱⁱ	2.55 (4)	2.35 (3)	2.63 (3)
Ge—Er	3.07 (2)	2.92 (3)	3.41 (3)
Ge—Er^iv	3.04 (2)	2.89 (2)	3.48 (3)
Ge—Er^v	3.05 (2)	2.89 (2)	3.48 (3)
Ge—Er^vi	3.08 (2)	2.92 (3)	3.41 (3)
Ge—Er^vii	3.03 (3)	2.84 (3)	3.17 (6)
Ge—Er^viii	3.03 (3)	2.84 (3)	3.17 (6)

Selected bond lengths (Å) for (VII) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.51 (6)	2.20 (6)	2.70 (7)
Ge—Geⁱⁱ	2.53 (5)	1.47 (5)	2.63 (5)
Ge—Geⁱⁱⁱ	2.53 (5)	1.47 (5)	2.63 (5)
Ge—Er	3.06 (3)	2.93 (4)	3.32 (3)
Ge—Er^iv	3.03 (3)	2.88 (3)	3.43 (3)
Ge—Er^v	3.03 (3)	2.88 (3)	3.43 (3)
Ge—Er^vi	3.06 (3)	2.93 (4)	3.32 (3)
Ge—Er^vii	3.05 (4)	2.87 (3)	3.20 (8)
Ge—Er^viii	3.05 (4)	2.87 (3)	3.20 (8)

Selected bond lengths (Å) for (VIII) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.51 (6)	2.18 (6)	2.72 (7)
Ge—Geⁱⁱ	2.53 (5)	1.50 (5)	2.63 (4)
Ge—Geⁱⁱⁱ	2.53 (5)	1.50 (5)	2.63 (4)
Ge—Er	3.06 (3)	2.88 (4)	3.36 (3)
Ge—Er^iv	3.03 (3)	2.86 (3)	3.40 (4)
Ge—Er^v	3.03 (3)	2.86 (3)	3.40 (4)
Ge—Er^vi	3.06 (3)	2.88 (4)	3.36 (3)
Ge—Er^vii	3.05 (4)	2.91 (4)	3.20 (8)
Ge—Er^viii	3.06 (4)	2.91 (4)	3.20 (8)

Selected bond lengths (Å) for (IX) top

	Average	Minimum	Maximum
Ge—Geⁱ	2.51 (6)	2.18 (6)	2.72 (7)
Ge—Geⁱⁱ	2.53 (5)	1.50 (5)	2.63 (4)
Ge—Geⁱⁱⁱ	2.53 (5)	1.50 (5)	2.63 (4)
Ge—Er	3.06 (3)	2.88 (4)	3.36 (3)
Ge—Er^iv	3.03 (3)	2.86 (3)	3.40 (4)
Ge—Er^v	3.03 (3)	2.86 (3)	3.40 (4)
Ge—Er^vi	3.06 (3)	2.88 (4)	3.36 (3)
Ge—Er^vii	3.05 (4)	2.91 (4)	3.20 (8)
Ge—Er^viii	3.06 (4)	2.91 (4)	3.20 (8)

Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
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Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
		Text
		Plain Text