Ca_1.5Eu₃Sn_0.5O₇: a calcium europium tin oxide with a novel structure

A new quaternary compound in the Ca-Eu-Sn-O system, namely calcium europium tin hepta­oxide, Ca_1.5Eu₃Sn_0.5O₇, was prepared by solid-state reaction at 2073 K. All atoms in the structure are on 4i special positions (on mirrors) in space group C2/m. Ca/Eu sites are situated within two O octa­hedra and within two sevenfold coordination sites surrounded by O-capped trigonal prisms. A Ca/Eu/Sn site is coordinated by five O atoms. The structural formula can be represented as (Ca_0.28Eu_0.72)(Ca_0.16Eu_0.84)(Ca_0.46Eu_0.54)(Ca_0.28Eu_0.72)(Ca_0.32Eu_0.18Sn_0.50)O₇. The crystal structure is a new type and is related to the structure of B-form Eu₂O₃.

S1. Comment

Recently, a new quaternary oxide, Ca_0.8Y_2.4Sn_0.8O₆, isostructural with Mg₃TeO₆ and a member of the Ca–Y–Sn–O system, was prepared by solid-state reaction (Kaminaga et al., 2006). In an attempt to substitute Eu atoms for all Y atoms in the compound, a mixture of the compound with the Mg₃TeO₆-type structure and CaSnO₃ with a perovskite-type structure was prepared at 1673 K. In order to make single crystals, we heated the sample to 2073 K and in fact obtained the title new quaternary compound with a new structure in the Ca–Eu–Sn–O system, and present its structure here.

A Ca:Eu:Sn molar ratio of 3:6:1 was measured for the single crystals obtained, using an energy-dispersive X-ray (EDX) analyser on a scanning electron microscope. The proportions of Eu and Sn in the crystals were lower than those in the starting materials (Ca:Eu:Sn = 1:3:1).

All metal (M) and O atoms are located on mirrors (4i special positions) with y = 0 and 1/2. After obtaining a starting model using SIR2004 (Burla et al. 2005), Eu atoms were tentatively placed at all M sites for the first step and their positions were refined. The bond-valence sums for the M sites, calculated with the bond lengths [Text missing?] and the bond-valence parameter of Eu^III—O^II = 2.076 (Brese & O'Keeffe, 1991), were 2.771, 2.943, 2.694, 2.947 and 3.785, respectively. Based on this information, we set four mixed sites of Ca and Eu atoms (Ca/Eu), where the bond-valence sums were below 3, and a Ca/Eu/Sn site with the bond valence above 3. In accordance with the composition analysed by EDX, the occupancy parameter of Sn at the Ca/Eu/Sn site was fixed at 0.5. The occupancy parameters of the Ca and Eu atoms at the sites of Ca1/Eu1, Ca2/Eu2, Ca3/Eu3, Ca4/Eu4 and Ca5/Eu5/Sn5 were refined to 0.278 (3)/0.722 (3), 0.165 (3)/0.835 (3), 0.458 (3)/0.542 (3), 0.281 (3)/0.719 (3) and 0.32 (19)/0.18 (5), respectively. The overall Ca:Eu:Sn molar ratio, calculated with these values, was in good agreement with the ratio from the EDX analysis (Ca:Eu:Sn = 3:6:1).

Fig. 1 shows the atomic arrangement around the M sites with Ca1/Eu1- and Ca2/Eu2-centred oxygen trigonal prisms. Ca1/Eu1 and Ca2/Eu2 sites are surrounded by six nearest O atoms which form trigonal prisms. The M—O bond lengths in the Ca1/Eu1- and Ca2/Eu2-centred prisms are 2.272 (6)–2.528 (4) Å and 2.288 (3)–2.488 (4) Å, respectively. The second-nearest neighbour O atoms, capping the widest rectangular plane of each trigonal prism, are located 2.606 (7) Å from Ca1/Eu1 and 2.716 (5) Å from Ca2/Eu2. Consequently, the corresponding metal atom sites are best described as seven-coordinated. The O atoms surrounding the Ca3/Eu3 and Ca4/Eu4 sites form distorted octahedra. The M—O bond lengths are 2.213 (5)–2.541 (4) Å (Ca3/Eu3—O) and 2.250 (3)–2.580 (4) Å (Ca4/Eu4—O). Second-nearest neighbour O atoms are located at distances of 3.204 (7) Å (Ca3/Eu3—O1) and 3.311 (9) Å (Ca4/Eu4—O6) Å. The Ca5/Eu5/Sn5 site is coordinated by five O atoms with bond lengths from 2.118 (3) to 2.386 (9) Å. The second-nearest neighbour O atom is 3.236 (5) Å from the Ca5/Eu5/Sn5 site.

The arrangement of M atoms around O atoms is shown in Fig. 2. Atoms O4, O5, O6 and O7 are surrounded by four M atoms, atom O1 by five M atoms, and atoms O2 and O3 by six M atoms. The equivalent isotropic displacement parameter of atom O6 is almost twice those of the other O atoms. This may result from the difference in the coordination environment around O6 compared with the others. Each O atom except O6 is located inside an M polyhedron, while atom O6^vi lies in a plane formed by Ca1/Eu1^xii, Ca1/Eu1^xiii and Ca5/Eu5/Sn5^vi [symmetry codes: (vi) ?; (xii) ?; (xiii) ? Please complete]. These three sites are parts of a distorted tetrahedron which is completed by Ca5/Eu5/Sn5^xv [symmetry code: (xv) ? Please complete]. The direction of the ellipsoid long axis is toward the Ca4/Eu4^vi and Ca5/Eu5/Sn5^xv sites, with distances of 3.311 (9) and 2.386 (9) Å, respectively.

We could not find any isotypic compound in the inorganic crystal structure database (ICSD, 2005). However, the crystal structure of Ca_1.5Eu₃Sn_0.5O₇ can be related to the structure of the B form of Eu₂O₃. This form is a mid-temperature monoclinic phase which is stable from 1423 to 2273 K, between the high-temperature A form hexagonal phase and the low-temperature C form cubic phase (Yakel, 1979). The space group of the B form of Eu₂O₃ is the same (C2/m) as that of Ca_1.5Eu₃Sn_0.5O₇. The refined unit-cell parameters of B-form Eu₂O₃ are a = 14.1105 (2) Å, b = 3.6021 (1) Å, c = 8.8080 (2) Å and β = 100.037 (1)°, and the unit-cell volume is 440.84 (3) ų. In the structure of B-form Eu₂O₃, there are three Eu sites and five O sites, all of which are also on 4i special positions with y = 0 and 1/2. The b axis lengths of B-form Eu₂O₃ and Ca_1.5Eu₃Sn_0.5O₇ [3.6294 (2) Å] are similar. The coordination environments of Eu1 and Eu2 are similar to those of Ca1/Eu1 and Ca2/Eu2 in Ca_1.5Eu₃Sn_0.5O₇. The Eu1—O bond lengths are 2.290 (2)–2.537 (2) Å (prism) and 2.656 (4) Å (cap), and the Eu2—O bond lengths are 2.288 (2)–2.462 (2) Å (prism) and 2.7394 (2) Å(cap). As with the Ca3/Eu3 and Ca4/Eu4 sites of the present structure of Ca_1.5Eu₃Sn_0.5O₇, in B-form Eu₂O₃ the Eu3 atoms are in a distorted O octahedron, with M—O bond lengths ranging from 2.239 (2) to 2.544 (1) Å. The second-nearest neighbour O atom is 3.133 (4) Å from Eu3.

The extended structure of Ca_1.5Eu₃Sn_0.5O₇ is illustrated in Fig. 3(a) with Ca1/Eu1- and Ca2/Eu2-centred O₆ trigonal prisms. The structure of B-form Eu₂O₃ is shown in Fig. 3(b) with Eu1- and Eu2-centred O₆ trigonal prisms. As shown in Fig. 4, pairs of Ca1/Eu1-centred prisms in Ca_1.5Eu₃Sn_0.5O₇, sharing O4—O4(symmetry code?) edges lying in the plane (501), stack parallel to the b-axis direction by sharing O3—O6 edges. Pairs of Ca2/Eu2-centred prisms, which share O7—O7(symmetry code?) edges lying in the (101) plane, stack parallel to the b-axis direction by sharing O3—O7 edges. Ca1/Eu1- and Ca2/Eu2-centred trigonal prism pairs share O3—O3(symmetry code?) edges and form trigonal prism layers in the (201) plane. Ca3/Eu3, Ca4/Eu4 and Ca5/Eu5/Sn5 atoms are located between the trigonal prism layers (Fig. 3a). A similar arrangement of prism pairs is seen in the structure of B-form Eu₂O₃, where the layers of Eu1- and Eu2-centred prism pairs share vertices and form tunnels parallel to the b-axis direction. Eu3 atoms are in sevenfold coordination sites in the tunnels.

S2. Experimental

The starting materials were powders of Eu₂O₃ (99.99% purity; Rare Metallic), CaCO₃ (99.99% purity; Rare Metallic) and SnO₂ (99.9% purity; Sigma–Aldrich). Y₂O₃ and SnO₂ powders were heated at 1273 K for 6 h before weighing. The powders were weighed and mixed in a Ca:Eu:Sn molar ratio of 1:3:1. The mixture was pressed into a pellet at 50 MPa and placed on a platinum–rhodium plate. The polycrystalline sample of Ca_1.5Eu₃Sn_0.5O₇ was prepared by reaction sintering at 2073 K with an electric furnace in air. After heating at this temperature for 12 h, the sample was cooled to room temperature in the furnace. The growth of grains was observed in the sample. A colourless translucent single-crystal platelet was selected from the grains. The compositions of Ca, Eu and Sn in the single-crystal were measured using a scanning electron microscope (SEM, Hitachi, S3000500N) with an energy dispersive X-ray spectrometer (EDX, HORIBA, EMAX-500).

S3. Refinement

The highest peak (1.517 Å⁻³) and deepest hole (−1.415 Å⁻³) in the F_o - F_c map were observed at (0.1437, 0.0000, 0.0666), 0.87 Å from O1, and at (0.3523, 0.0000, 0.4679), 0.63 Å from Eu4, respectively.

Computing details

Data collection: PROCESS-AUTO (Rigaku/MSC, 2005); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2005); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 1999); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The O-atom coordination around five M sites in the structure of Ca1.5Eu3Sn0.5O7, showing Ca1/Eu1- and Ca2/Eu2-centred O6 trigonal prisms. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes as in Table 1; additionally: (x) −x + 1/2, −y + 1/2, z; (xi) x + 1/2, y − 1/2 z + 1.]
	Fig. 2. The M-atom coordination around O sites. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes as in Table 1; additionally: (xii) x + 1/2, y − 1/2, z; (xiii) x + 1/2, y + 1/2, z; (xiv) −x + 1/2, −y + 1/2, −z; (xv) Text missing?; (xii) x + 1/2, y − 1/2, z + 1.]
	Fig. 3. (a) The extended structure of Ca1.5Eu3Sn0.5O7, illustrated with Ca1/Eu1- and Ca2/Eu2-centred O6 trigonal prisms. (b) The structure of B-form Eu2O3, illustrated with Eu1- and Eu2-centred O6 trigonal prisms.
	Fig. 4. The arrangement of Ca1/Eu1-centred and Ca2/Eu2-centred O6 trigonal prisms in Ca1.5Eu3Sn0.5O7.

calcium europium tin heptaoxide

Crystal data

Ca1.5Eu3O7Sn0.5	F(000) = 1200
Mr = 687.35	Dx = 6.384 Mg m^−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -C 2y	Cell parameters from 1000 reflections
a = 22.8628 (11) Å	θ = 3.1–27.5°
b = 3.6294 (2) Å	µ = 28.75 mm^−1
c = 9.0610 (4) Å	T = 296 K
β = 107.9150 (14)°	Platelet, colourless
V = 715.41 (6) Å^3	0.07 × 0.05 × 0.03 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID diffractometer	945 independent reflections
Radiation source: fine-focus sealed tube	858 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.059
Detector resolution: 10.00 pixels mm^-1	θmax = 27.4°, θmin = 3.4°
ω scans	h = −27→28
Absorption correction: numerical (NUMABS; Higashi, 1999)	k = −4→4
Tmin = 0.276, Tmax = 0.719	l = −11→11
3610 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F^2 > 2σ(F^2)] = 0.026	Secondary atom site location: difference Fourier map
wR(F^2) = 0.061	w = 1/[σ^2(Fo^2) + 4.2873P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
945 reflections	Δρmax = 1.52 e Å^−3
73 parameters	Δρmin = −1.42 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ca1	0.03264 (2)	0.0000	0.71401 (5)	0.01056 (14)	0.28
Eu1	0.03264 (2)	0.0000	0.71401 (5)	0.01056 (14)	0.72
Ca2	0.186221 (18)	0.0000	0.86957 (4)	0.00880 (14)	0.16
Eu2	0.186221 (18)	0.0000	0.86957 (4)	0.00880 (14)	0.84
Ca3	0.21609 (3)	0.0000	0.32017 (6)	0.01153 (15)	0.46
Eu3	0.21609 (3)	0.0000	0.32017 (6)	0.01153 (15)	0.54
Ca4	0.11926 (2)	0.5000	0.50076 (5)	0.01370 (15)	0.28
Eu4	0.11926 (2)	0.5000	0.50076 (5)	0.01370 (15)	0.72
Ca5	0.07728 (2)	0.5000	0.06738 (6)	0.01160 (16)	0.32
Eu5	0.07728 (2)	0.5000	0.06738 (6)	0.01160 (16)	0.18
Sn5	0.07728 (2)	0.5000	0.06738 (6)	0.01160 (16)	0.50
O1	0.1080 (3)	0.0000	0.9960 (8)	0.0373 (16)
O2	0.2032 (2)	0.0000	0.5857 (6)	0.0231 (14)
O3	0.1127 (3)	0.5000	0.7480 (6)	0.0218 (12)
O4	0.0589 (3)	0.0000	0.4777 (6)	0.0257 (13)
O5	0.1521 (3)	0.5000	0.2891 (6)	0.0200 (12)
O6	0.0042 (4)	0.5000	0.1722 (9)	0.050 (2)
O7	0.2516 (3)	0.0000	0.1189 (5)	0.0168 (11)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ca1	0.0109 (3)	0.0113 (3)	0.0094 (2)	0.000	0.00318 (16)	0.000
Eu1	0.0109 (3)	0.0113 (3)	0.0094 (2)	0.000	0.00318 (16)	0.000
Ca2	0.0080 (2)	0.0077 (2)	0.0092 (2)	0.000	0.00038 (15)	0.000
Eu2	0.0080 (2)	0.0077 (2)	0.0092 (2)	0.000	0.00038 (15)	0.000
Ca3	0.0133 (3)	0.0087 (3)	0.0160 (3)	0.000	0.0095 (2)	0.000
Eu3	0.0133 (3)	0.0087 (3)	0.0160 (3)	0.000	0.0095 (2)	0.000
Ca4	0.0191 (3)	0.0107 (3)	0.0154 (3)	0.000	0.01123 (19)	0.000
Eu4	0.0191 (3)	0.0107 (3)	0.0154 (3)	0.000	0.01123 (19)	0.000
Ca5	0.0098 (3)	0.0125 (3)	0.0107 (3)	0.000	0.0005 (2)	0.000
Eu5	0.0098 (3)	0.0125 (3)	0.0107 (3)	0.000	0.0005 (2)	0.000
Sn5	0.0098 (3)	0.0125 (3)	0.0107 (3)	0.000	0.0005 (2)	0.000
O1	0.034 (4)	0.041 (5)	0.044 (4)	0.000	0.023 (3)	0.000
O2	0.023 (3)	0.024 (4)	0.022 (3)	0.000	0.007 (2)	0.000
O3	0.023 (3)	0.019 (3)	0.019 (3)	0.000	0.000 (2)	0.000
O4	0.015 (3)	0.037 (4)	0.024 (3)	0.000	0.004 (2)	0.000
O5	0.022 (3)	0.019 (3)	0.020 (3)	0.000	0.007 (2)	0.000
O6	0.060 (5)	0.032 (5)	0.073 (5)	0.000	0.042 (4)	0.000
O7	0.020 (3)	0.017 (3)	0.011 (2)	0.000	0.003 (2)	0.000

Geometric parameters (Å, º)

Ca1/Eu1—O4^i	2.272 (6)	Ca3/Eu3—O2	2.513 (5)
Ca1/Eu1—O6^ii	2.367 (4)	Ca3/Eu3—O2^iii	2.541 (4)
Ca1/Eu1—O4	2.395 (5)	Ca4/Eu4—O4	2.250 (3)
Ca1/Eu1—O3	2.528 (4)	Ca4/Eu4—O5	2.264 (5)
Ca1/Eu1—O1	2.606 (7)	Ca4/Eu4—O3	2.291 (5)
Ca2/Eu2—O7^iii	2.288 (3)	Ca4/Eu4—O2	2.580 (4)
Ca2/Eu2—O7^iv	2.293 (5)	Ca4/Eu4—O6	3.311 (9)
Ca2/Eu2—O1	2.402 (6)	Ca5/Eu5/Sn5—O1^v	2.118 (3)
Ca2/Eu2—O3	2.488 (4)	Ca5/Eu5/Sn5—O6	2.160 (7)
Ca2/Eu2—O2	2.716 (5)	Ca5/Eu5/Sn5—O5	2.202 (5)
Ca3/Eu3—O7	2.213 (5)	Ca5/Eu5/Sn5—O6^vi	2.386 (9)
Ca3/Eu3—O5	2.293 (4)
O3—Ca1/Eu1—O1	69.19 (14)	O4—Ca4/Eu4—O2^ix	166.72 (16)
O4—Ca1/Eu1—O3	74.78 (15)	O1^x—Ca5/Eu5/Sn5—O6^vi	87.8 (2)
O6^ii—Ca1/Eu1—O3	74.82 (18)	O6—Ca5/Eu5/Sn5—O6^vi	84.6 (3)
O4^i—Ca1/Eu1—O4	75.0 (2)	O1^x—Ca5/Eu5/Sn5—O5	92.4 (2)
O6^i—Ca1/Eu1—O1	77.8 (2)	O6—Ca5/Eu5/Sn5—O5	95.0 (3)
O4^i—Ca1/Eu1—O6^ii	88.0 (2)	O1^v—Ca5/Eu5/Sn5—O1^x	117.9 (3)
O3—Ca1/Eu1—O3^vii	91.73 (19)	O1^x—Ca5/Eu5/Sn5—O6	120.55 (15)
O6^ii—Ca1/Eu1—O6^i	100.1 (3)	O5—Ca5/Eu5/Sn5—O6^vi	179.7 (2)
O4^i—Ca1/Eu1—O3	123.74 (13)	Ca1/Eu1^ii—O6—Ca4/Eu4	84.2 (2)
O4—Ca1/Eu1—O1	127.18 (18)	Ca1/Eu1^ix—O3—Ca1/Eu1	91.73 (19)
O6^ii—Ca1/Eu1—O4	127.62 (15)	Ca1/Eu1^ii—O6—Ca5/Eu5/Sn5^vi	96.5 (3)
O6^i—Ca1/Eu1—O3	147.0 (2)	Ca1/Eu1^i—O4—Ca1/Eu1	105.0 (2)
O4^i—Ca1/Eu1—O1	157.8 (2)	Ca1/Eu1^ii—O6—Ca1/Eu1^i	100.1 (3)
O1—Ca2/Eu2—O3	73.18 (16)	Ca2/Eu2—O3—Ca1/Eu1	84.01 (4)
O7^viii—Ca2/Eu2—O7^iv	75.36 (14)	Ca2/Eu2—O1—Ca1/Eu1	84.11 (19)
O7^viii—Ca2/Eu2—O3	76.55 (15)	Ca2/Eu2^ix—O3—Ca2/Eu2	93.65 (18)
O7^viii—Ca2/Eu2—O2	77.04 (14)	Ca2/Eu2^iii—O7—Ca2/Eu2^xi	104.64 (14)
O3—Ca2/Eu2—O2	81.64 (14)	Ca2/Eu2^viii—O7—Ca2/Eu2^iii	105.0 (2)
O7^iv—Ca2/Eu2—O1	83.4 (2)	Ca2/Eu2—O3—Ca1/Eu1^ix	160.5 (2)
O3^vii—Ca2/Eu2—O3	93.65 (19)	Ca3/Eu3^viii—O2—Ca4/Eu4	89.689 (14)
O7^viii—Ca2/Eu2—O7^iii	105.0 (2)	Ca3/Eu3^viii—O2—Ca2/Eu2	89.01 (13)
O7^viii—Ca2/Eu2—O1	121.43 (13)	Ca3/Eu3—O2—Ca4/Eu4	90.57 (14)
O7^iv—Ca2/Eu2—O3	125.65 (11)	Ca3/Eu3^viii—O2—Ca3/Eu3^iii	91.13 (17)
O7^iv—Ca2/Eu2—O2	133.87 (17)	Ca3/Eu3—O2—Ca3/Eu3^viii	91.96 (14)
O1—Ca2/Eu2—O2	142.7 (2)	Ca3/Eu3—O7—Ca2/Eu2^viii	110.03 (14)
O7^iii—Ca2/Eu2—O3	157.57 (17)	Ca3/Eu3^ix—O5—Ca3/Eu3	104.6 (2)
O5—Ca3/Eu3—O2	81.90 (15)	Ca3/Eu3—O7—Ca2/Eu2^xi	121.3 (2)
O7—Ca3/Eu3—O2^viii	82.18 (15)	Ca3/Eu3^iii—O2—Ca4/Eu4	177.3 (2)
O2—Ca3/Eu3—O2^viii	88.04 (14)	Ca3/Eu3—O2—Ca2/Eu2	178.6 (2)
O2^viii—Ca3/Eu3—O2^iii	91.13 (17)	Ca4/Eu4—O2—Ca2/Eu2	88.44 (14)
O5^vii—Ca3/Eu3—O2^iii	81.15 (14)	Ca4/Eu4^vii—O2—Ca4/Eu4	89.38 (17)
O7—Ca3/Eu3—O5	106.30 (15)	Ca4/Eu4—O3—Ca1/Eu1	98.25 (15)
O5^vii—Ca3/Eu3—O5	104.6 (2)	Ca4/Eu4—O3—Ca2/Eu2	101.22 (17)
O7—Ca3/Eu3—O2	165.99 (18)	Ca4/Eu4^vii—O4—Ca1/Eu1	103.44 (16)
O5—Ca3/Eu3—O2^iii	167.49 (17)	Ca4/Eu4—O5—Ca3/Eu3	105.15 (16)
O4—Ca4/Eu4—O6	67.79 (14)	Ca4/Eu4—O4—Ca4/Eu4^vii	107.5 (2)
O5—Ca4/Eu4—O6	67.49 (18)	Ca4/Eu4—O4—Ca1/Eu1^i	117.72 (15)
O4—Ca4/Eu4—O2	80.72 (14)	Ca5/Eu5/Sn5—O6—Ca4/Eu4	83.5 (3)
O5—Ca4/Eu4—O2	80.95 (15)	Ca5/Eu5/Sn5—O6—Ca5/Eu5/Sn5^vi	95.4 (3)
O4—Ca4/Eu4—O3	82.42 (16)	Ca5/Eu5/Sn5^iv—O1—Ca1/Eu1	96.8 (2)
O3—Ca4/Eu4—O2	88.54 (15)	Ca5/Eu5/Sn5—O5—Ca4/Eu4	113.9 (2)
O2^ix—Ca4/Eu4—O2	89.38 (17)	Ca5/Eu5/Sn5—O5—Ca3/Eu3	113.52 (15)
O4—Ca4/Eu4—O5	105.97 (16)	Ca5/Eu5/Sn5^xii—O1—Ca5/Eu5/Sn5^iv	117.9 (3)
O4—Ca4/Eu4—O4^ix	107.5 (2)	Ca5/Eu5/Sn5^iv—O1—Ca2/Eu2	120.75 (14)
O2—Ca4/Eu4—O6	125.47 (11)	Ca5/Eu5/Sn5—O6—Ca1/Eu1^ii	128.21 (16)
O3—Ca4/Eu4—O6	127.35 (18)	Ca5/Eu5/Sn5^vi—O6—Ca4/Eu4	178.9 (3)
O5—Ca4/Eu4—O3	165.16 (19)

Symmetry codes: (i) −x, −y, −z+1; (ii) −x, −y+1, −z+1; (iii) −x+1/2, −y−1/2, −z+1; (iv) x, y, z+1; (v) x, −y, z−1; (vi) −x, −y+1, −z; (vii) x, y−1, z; (viii) −x+1/2, −y+1/2, −z+1; (ix) x, y+1, z; (x) x, y+1, z−1; (xi) x, y, z−1; (xii) x, y−1, z+1.