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A new quaternary oxide, calcium yttrium stannate, Ca0.8Y2.4Sn0.8O6, is isostructural with Mg3TeO6 (trigonal, R\overline{3}). The empirical formula can be expressed as (Ca0.2667Y0.7333)6(Y0.4Sn0.6)SnO12. The Ca/Y site has a distorted coordination octa­hedron of O atoms, with Ca/Y-O distances ranging from 2.227 (3) to 2.350 (3) Å, while the octa­hedra of O atoms that coordinate to the Sn and Y/Sn sites are nearly regular, with an Sn-O distance of 2.066 (2) Å and a Y/Sn-O distance of 2.147 (3) Å.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106017586/fa3014sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270106017586/fa3014Isup2.hkl
Contains datablock I

Comment top

New quaternary compounds have recently been found in addition to the previously known CaO–Y2O3–SiO2 (Nagasawa et al., 1998) and CaO–Y2O3–GeO2 systems (Yamane et al., 2006). Since no quaternary compound had been reported for the CaO–Y2O3–SnO2 system, we have carried out a materials survey for this system. As a result, the new quaternary compound Ca0.8Y2.4Sn0.8O6 was prepared by solid-state reaction. The crystal structure of Ca0.8Y2.4Sn0.8O6 reveals that it has the same structure type as Mg3TeO6, in which Te atoms are located at the 3a and 3b special positions in space group R3, while the Mg and O atoms are at general (18f) positions (Newnham et al., 1970, Schulz & Bayer, 1971).

In the starting model, Sn and Y atoms were placed statistically at the 3a and 3b sites and Ca and Y atoms at an 18f site. The occupancies at the Ca1/Y1, Sn1 and Y2/Sn2 sites were refined to values of 0.270 (3)/0.730 (3), 0.996 (3) and 0.404 (4)/0.596 (4), respectively, giving the Ca:Y:Sn molar ratio 1:3:1. This ratio agrees with the initial molar ratio of metal elements in the mixture used in the synthesis. For the final refinement, the occupation parameters were fixed at values of 0.2667/0.7333, 1.0 and 0.40/0.60 for Ca1/Y1, Sn1 and Y2/Sn2. The structure formula of Ca0.8Y2.4Sn0.8O6 can be expressed as (Ca0.2667Y0.7333)6(Y0.4Sn0.6)SnO12.

Fig. 1 shows the O-atom coordination surrounding the Ca1/Y1 and Sn sites. The extended structure, illustrated by the Sn1- and Y2/Sn2-centered oxygen octahedra, is shown in Fig. 2. Table 1 lists selected interatomic distances and angles. The Sn1—O1 distance in the Sn1(O1)6 octahedron is 2.066 (2) Å, which is in good agreement with the Sn—O distances (2.061–2.063 Å) reported for CaSnO3 and SrSnO3, which have the perovskite-type structure (Vegas et al., 1986). The bond valence sum for Sn1, calculated with the bond valence parameter of SnIV—OII (1.905 Å) was 3.848 (Brese & O'Keeffe, 1991). The value is close to the formal valence of SnIV. The Y2/Sn2—O2 distance in the Y2/Sn2(O2)6 octahedron is 2.147 (3) Å. This value is longer than that in the Sn1(O1)6 octahedron, consistent with the statistical occupation of Sn and Y atoms in the same site with an occupancy ratio Sn:Y of 0.6:0.4. The Ca1/Y1 site is surrounded by six O atoms in the three O1 and three O2 sites, with Ca1/Y1—O1 and Ca1/Y1—O2 distances in the range 2.227 (3) to 2.350 (3) Å, with an average value of 2.308 Å. The bond valence sum for Ca, calculated with the bond valence parameter of CaII—OII (1.967 Å), is 2.409 and that of Y, with the parameter of YIII—OII (2.014 Å), is 2.735. These results agree with a mixed occupation of Ca and Y atoms in the 18f site with a Ca:Y ratio of 0.2667:0.7333.

In the quaternary compounds prepared in the CaO–Y2O3–SiO2 and CaO–Y2O3–GeO2 systems, coordination numbers for Ca and Y range from six to eight, and Si or Ge atoms lie in tetrahedral sites. However, all cations in Ca0.8Y2.4Sn0.8O6 are in sixfold coordination sites, surrounded by oxygen octahedra. The bond length distortion, octahedral edge length distortion and octahedral angle variance defined by Renner & Lehmann (1986) are 0%, 3.62% and 1.70° for Sn1(O1)6, 0%, 6.63% and 5.76° for Y2/Sn2(O1)6, and 5.23%, 10.02% and 25.07° for Ca1/Y1(O1,2)6, respectively. These values indicate that the Ca1/Y1(O1,2)6 octahedron is the most distorted in the structure. This octahedron shares an edge of length 2.832 (2) Å with Y2/Sn2(O2)6, another edge of length 2.815 (4) Å with Sn1(O1)6, and four edges [2.972 (2)–2.987 (3) Å, average 2.973 Å] with a related Ca1/Y1(O1,2)6 unit.

Experimental top

The starting materials were powders of Y2O3 (99.99% purity; Nippon Yttrium), 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 Ca:Y:Sn molar ratio of 1:3:1. The mixture was pressed into a pellet at 50 MPa and placed on a platinum plate. The polycrystalline sample of Ca0.8Y2.4Sn0.8O6 was prepared by reaction sintering at 1400 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. Grain growth in the sample was observed upon heating at 1773 K for 24 h. A colorless granular single-crystal with a size less than 0.08 × 0.08 × 0.07 mm was selected from the resulting grains.

Computing details top

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

Figures top
[Figure 1] Fig. 1. The arrangement of atomic positions in the structure of Ca0.8Y2.4Sn0.8O6, with 99% probability displacement ellipsoids. Please define all symmetry codes.
[Figure 2] Fig. 2. The crystal structure of Ca0.8Y2.4Sn0.8O6 in a representation using oxygen-centered Sn1 and Y2/Sn2 octahedra.
(I) top
Crystal data top
Ca0.8O6Sn0.8Y2.4Dx = 5.051 Mg m3
Mr = 436.40Mo Kα radiation, λ = 0.710747 Å
Trigonal, R3Cell parameters from 2701 reflections
Hall symbol: -R 3θ = 3.1–27.5°
a = 9.509 (5) ŵ = 28.19 mm1
c = 10.989 (8) ÅT = 296 K
V = 860.5 (9) Å3Granule, colourless
Z = 60.08 × 0.08 × 0.07 mm
F(000) = 1186
Data collection top
Rigaku R-AXIS RAPID
diffractometer
445 independent reflections
Radiation source: fine-focus sealed tube430 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.053
Detector resolution: 10.00 pixels mm-1θmax = 27.5°, θmin = 3.1°
ω scansh = 1112
Absorption correction: numerical
(ABSCOR; Higashi, 1999)
k = 1212
Tmin = 0.101, Tmax = 0.123l = 1414
2843 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.018 w = 1/[σ2(Fo2) + 1.9055P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.041(Δ/σ)max < 0.001
S = 1.18Δρmax = 0.63 e Å3
445 reflectionsΔρmin = 0.60 e Å3
33 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0044 (2)
Crystal data top
Ca0.8O6Sn0.8Y2.4Z = 6
Mr = 436.40Mo Kα radiation
Trigonal, R3µ = 28.19 mm1
a = 9.509 (5) ÅT = 296 K
c = 10.989 (8) Å0.08 × 0.08 × 0.07 mm
V = 860.5 (9) Å3
Data collection top
Rigaku R-AXIS RAPID
diffractometer
445 independent reflections
Absorption correction: numerical
(ABSCOR; Higashi, 1999)
430 reflections with I > 2σ(I)
Tmin = 0.101, Tmax = 0.123Rint = 0.053
2843 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.01833 parameters
wR(F2) = 0.0410 restraints
S = 1.18Δρmax = 0.63 e Å3
445 reflectionsΔρmin = 0.60 e Å3
Special details top

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 (Å2) top
xyzUiso*/UeqOcc. (<1)
Ca10.26795 (4)0.22760 (4)0.29390 (3)0.00538 (16)0.2667
Y10.26795 (4)0.22760 (4)0.29390 (3)0.00538 (16)0.7333
Sn10.00000.00000.50000.00499 (17)
Y20.00000.00000.00000.00420 (18)0.4
Sn20.00000.00000.00000.00420 (18)0.6
O10.0278 (3)0.1830 (3)0.3839 (2)0.0089 (5)
O20.2087 (3)0.1806 (3)0.0968 (2)0.0118 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ca10.0058 (2)0.0051 (2)0.0057 (2)0.00309 (16)0.00002 (13)0.00020 (12)
Y10.0058 (2)0.0051 (2)0.0057 (2)0.00309 (16)0.00002 (13)0.00020 (12)
Sn10.0046 (2)0.0046 (2)0.0058 (3)0.00229 (10)0.0000.000
Y20.0039 (2)0.0039 (2)0.0048 (3)0.00195 (11)0.0000.000
Sn20.0039 (2)0.0039 (2)0.0048 (3)0.00195 (11)0.0000.000
O10.0100 (12)0.0053 (11)0.0107 (13)0.0034 (10)0.0006 (9)0.0027 (9)
O20.0153 (13)0.0168 (13)0.0082 (13)0.0117 (12)0.0001 (10)0.0001 (9)
Geometric parameters (Å, º) top
Ca1/Y1—O22.227 (3)Sn1—O12.066 (2)
Ca1/Y1—O1i2.280 (3)Sn1—O1vii2.066 (2)
Ca1/Y1—O12.325 (2)Sn1—O1viii2.066 (2)
Ca1/Y1—O1ii2.328 (3)Y2/Sn2—O2ix2.147 (3)
Ca1/Y1—O2iii2.335 (3)Y2/Sn2—O22.147 (3)
Ca1/Y1—O2iv2.350 (3)Y2/Sn2—O2x2.147 (3)
Sn1—O1v2.066 (2)Y2/Sn2—O2ii2.147 (3)
Sn1—O1vi2.066 (2)Y2/Sn2—O2xi2.147 (3)
Sn1—O1ii2.066 (2)Y2/Sn2—O2v2.147 (3)
O1—Ca1/Y1—O1ii74.42 (11)O1v—Sn1—O1viii94.14 (10)
O1ii—Ca1/Y1—O2iii79.60 (8)O2—Y2/Sn2—O2x82.41 (9)
O1i—Ca1/Y1—O180.37 (8)O2ix—Y2/Sn2—O2ii82.41 (9)
O1i—Ca1/Y1—O2iv80.27 (8)O2—Y2/Sn2—O2xi82.41 (9)
O1ii—Ca1/Y1—O2iv96.64 (9)O2x—Y2/Sn2—O2v82.41 (9)
O1—Ca1/Y1—O2iv110.38 (9)O2ii—Y2/Sn2—O2xi82.41 (9)
O1i—Ca1/Y1—O2iii125.35 (8)O2ix—Y2/Sn2—O2v82.41 (9)
O1i—Ca1/Y1—O1ii151.77 (5)O2—Y2/Sn2—O2v97.59 (9)
O1—Ca1/Y1—O2iii153.95 (8)O2ii—Y2/Sn2—O2v97.59 (9)
O2iii—Ca1/Y1—O2iv74.28 (12)O2ix—Y2/Sn2—O2x97.59 (9)
O2—Ca1/Y1—O2iii80.38 (9)O2—Y2/Sn2—O2ii97.59 (9)
O2—Ca1/Y1—O1i92.93 (8)O2x—Y2/Sn2—O2xi97.59 (9)
O2—Ca1/Y1—O1104.50 (9)O2ix—Y2/Sn2—O2xi97.59 (9)
O2—Ca1/Y1—O1ii105.40 (9)Ca1/Y1iii—O2—Ca1/Y1xii97.05 (9)
O2—Ca1/Y1—O2iv142.61 (8)Ca1/Y1i—O1—Ca1/Y1v99.24 (8)
O1vi—Sn1—O1viii85.86 (10)Ca1/Y1—O2—Ca1/Y1iii99.62 (9)
O1vii—Sn1—O1viii85.86 (10)Ca1/Y1i—O1—Ca1/Y199.63 (8)
O1vi—Sn1—O1vii85.86 (10)Ca1/Y1—O2—Ca1/Y1xii120.13 (11)
O1ii—Sn1—O185.86 (10)Ca1/Y1—O1—Ca1/Y1v124.66 (11)
O1v—Sn1—O185.86 (10)Sn1—O1—Ca1/Y1v96.58 (9)
O1v—Sn1—O1ii85.86 (10)Sn1—O1—Ca1/Y196.68 (9)
O1vi—Sn1—O1ii94.14 (10)Sn1—O1—Ca1/Y1i144.93 (12)
O1vi—Sn1—O194.14 (10)Y2/Sn2—O2—Ca1/Y1xii99.28 (10)
O1v—Sn1—O1vii94.14 (10)Y2/Sn2—O2—Ca1/Y1iii99.75 (9)
O1ii—Sn1—O1vii94.14 (10)Y2/Sn2—O2—Ca1/Y1133.03 (12)
O1—Sn1—O1viii94.14 (10)
Symmetry codes: (i) x+1/3, y+2/3, z+2/3; (ii) x+y, x, z; (iii) x+2/3, y+1/3, z+1/3; (iv) y+2/3, xy+1/3, z+1/3; (v) y, xy, z; (vi) y, x+y, z+1; (vii) x, y, z+1; (viii) xy, x, z+1; (ix) x, y, z; (x) xy, x, z; (xi) y, x+y, z; (xii) x+y+1/3, x+2/3, z1/3.

Experimental details

Crystal data
Chemical formulaCa0.8O6Sn0.8Y2.4
Mr436.40
Crystal system, space groupTrigonal, R3
Temperature (K)296
a, c (Å)9.509 (5), 10.989 (8)
V3)860.5 (9)
Z6
Radiation typeMo Kα
µ (mm1)28.19
Crystal size (mm)0.08 × 0.08 × 0.07
Data collection
DiffractometerRigaku R-AXIS RAPID
diffractometer
Absorption correctionNumerical
(ABSCOR; Higashi, 1999)
Tmin, Tmax0.101, 0.123
No. of measured, independent and
observed [I > 2σ(I)] reflections
2843, 445, 430
Rint0.053
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.041, 1.18
No. of reflections445
No. of parameters33
Δρmax, Δρmin (e Å3)0.63, 0.60

Computer programs: PROCESS-AUTO (Rigaku/MSC & Rigaku Corporation, 2005), PROCESS-AUTO, CrystalStructure (Rigaku/MSC & Rigaku Corporation, 2005), SHELXL97 (Sheldrick, 1997), ATOMS (Dowty, 1999), SHELXL97.

Selected geometric parameters (Å, º) top
Ca1/Y1—O22.227 (3)Ca1/Y1—O2iii2.335 (3)
Ca1/Y1—O1i2.280 (3)Ca1/Y1—O2iv2.350 (3)
Ca1/Y1—O12.325 (2)Sn1—O12.066 (2)
Ca1/Y1—O1ii2.328 (3)Y2/Sn2—O22.147 (3)
O1—Ca1/Y1—O1ii74.42 (11)O2—Ca1/Y1—O2iii80.38 (9)
O1ii—Ca1/Y1—O2iii79.60 (8)O2—Ca1/Y1—O1i92.93 (8)
O1i—Ca1/Y1—O180.37 (8)O2—Ca1/Y1—O1104.50 (9)
O1i—Ca1/Y1—O2iv80.27 (8)O2—Ca1/Y1—O1ii105.40 (9)
O1ii—Ca1/Y1—O2iv96.64 (9)O1v—Sn1—O1vi85.86 (10)
O1—Ca1/Y1—O2iv110.38 (9)O1v—Sn1—O1ii94.14 (10)
O1i—Ca1/Y1—O2iii125.35 (8)O2—Y2/Sn2—O2vii82.41 (9)
O2iii—Ca1/Y1—O2iv74.28 (12)O2—Y2/Sn2—O2viii97.59 (9)
Symmetry codes: (i) x+1/3, y+2/3, z+2/3; (ii) x+y, x, z; (iii) x+2/3, y+1/3, z+1/3; (iv) y+2/3, xy+1/3, z+1/3; (v) y, x+y, z+1; (vi) xy, x, z+1; (vii) xy, x, z; (viii) y, xy, z.
 

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