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Dysprosium disilicate (Dy2Si2O7) is triclinic with a = 6.6158 (2), b = 6.6604 (2), c = 12.0551 (4) Å, α = 94.373 (2), β = 90.836 (2), γ = 91.512 (2)°, V = 529.4 (1) Å3, space group P\overline 1, Z = 4 and Dx = 6.156 g cm−3. The structure (single-crystal X-ray, R = 0.033, wR = 0.041) is built from a linear triple tetrahedral group [Si3O10] and isolated [SiO4] tetrahedron cross-linked by Dy3+ in one sixfold and three eightfold coordinated positions, and corresponds to the presently revised type B structure of Ho2Si2O7. The formation of the unusual linear triple tetrahedral group in the type B structure allows for a more continuous transition in the mean size of REE3+On (REE = rare earth element) polyhedra in REE disilicates through the 4f transition metal series. The crystal of Dy2Si2O7 investigated was complexly twinned such that the diffraction pattern was also consistent with a larger dimensionally monoclinic unit cell (a = 22.5354, b = 14.2102, c = 6.6158 Å, β = 91.788°), which resulted in an apparent superstructure of the type B structure in space group C1. Lattice coincidence with the type B unit cell appears to have been maintained during crystal synthesis and quenching by the complex sector-zoned growth twin.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768100008545/br0099sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108768100008545/br0099sup2.hkl
Supplementary material

Computing details top

Data collection: COLLECT (Nonius, 1997); cell refinement: COLLECT (Nonius, 1997); data reduction: SUNY Buffalo DATAP77; program(s) used to solve structure: SHELXTL PC Siemens; program(s) used to refine structure: SUNY Buffalo LINEX77; molecular graphics: Shape Software ATOMS, ORTEP-3 for Windows.

dysprosium disilicate top
Crystal data top
Dy2Si2O7Z = 4
Mr = 493.17Dx = 6.156 Mg m3
Triclinic, P1Mo Kα radiation, λ = 0.70926 Å
a = 6.6158 (2) ÅCell parameters from 32768 reflections
b = 6.6604 (2) Åθ = 2–35°
c = 12.0551 (4) ŵ = 28.45 mm1
α = 94.373 (2)°T = 293 K
β = 90.836 (2)°Prism, colorless
γ = 91.512 (2)°0.11 × 0.10 × 0.05 mm
V = 529.39 Å3
Data collection top
Nonius KappaCCD
diffractometer
4470 independent reflections
Radiation source: fine-focus sealed tube3220 reflections with I 3σ(I)
Graphite monochromatorRint = 0.107
area detector and scansθmax = 35°, θmin = 2°
Absorption correction: gaussian
(Coppens, Leiserowitz & Rabinovich, 1965)
h = 1010
Tmin = 0.144, Tmax = 0.380k = 59
32768 measured reflectionsl = 019
Refinement top
Refinement on FPrimary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033w = 1/[σ(F)2 + (0.025F)2], except w = 0 if I < 3σ(I)
wR(F2) = 0.041(Δ/σ)max = 0.001
S = 0.98Δρmax = 4.65 e Å3
4470 reflectionsΔρmin = 4.70 e Å3
204 parametersExtinction correction: B-C type 1 Lorentzian isotropic, Coppens & Hamilton (1970)
0 restraintsExtinction coefficient: 0.31 (2)
Crystal data top
Dy2Si2O7γ = 91.512 (2)°
Mr = 493.17V = 529.39 Å3
Triclinic, P1Z = 4
a = 6.6158 (2) ÅMo Kα radiation
b = 6.6604 (2) ŵ = 28.45 mm1
c = 12.0551 (4) ÅT = 293 K
α = 94.373 (2)°0.11 × 0.10 × 0.05 mm
β = 90.836 (2)°
Data collection top
Nonius KappaCCD
diffractometer
4470 independent reflections
Absorption correction: gaussian
(Coppens, Leiserowitz & Rabinovich, 1965)
3220 reflections with I 3σ(I)
Tmin = 0.144, Tmax = 0.380Rint = 0.107
32768 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.033204 parameters
wR(F2) = 0.0410 restraints
S = 0.98Δρmax = 4.65 e Å3
4470 reflectionsΔρmin = 4.70 e Å3
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Dy(1)0.94853 (4)0.33132 (4)0.11643 (2)0.00588 (9)
Dy(2)0.88556 (4)0.09387 (4)0.35971 (2)0.00579 (9)
Dy(3)0.37254 (4)0.78116 (4)0.36895 (2)0.00749 (9)
Dy(4)0.66787 (4)0.82973 (4)0.10747 (2)0.00742 (9)
Si(1)0.1553 (2)0.8528 (2)0.1164 (1)0.0048 (3)
Si(2)0.4873 (3)0.3370 (2)0.1759 (1)0.0061 (3)
Si(3)0.3777 (3)0.2743 (2)0.4048 (1)0.0064 (3)
Si(4)0.1433 (3)0.3702 (2)0.6180 (1)0.0056 (3)
O(1)0.6418 (6)0.4938 (6)0.1256 (3)0.0076 (7)
O(2)0.6179 (7)0.1419 (6)0.2095 (4)0.0120 (8)
O(3)0.2978 (7)0.2990 (7)0.0947 (3)0.0097 (8)
O(4)0.4055 (6)0.4283 (6)0.3065 (3)0.0072 (7)
O(5)0.5836 (7)0.1702 (6)0.4454 (4)0.0090 (8)
O(6)0.2276 (6)0.0965 (6)0.3755 (4)0.0100 (8)
O(7)0.2885 (7)0.4229 (6)0.5118 (3)0.0093 (8)
O(8)0.2841 (7)0.2167 (7)0.6875 (4)0.0118 (8)
O(9)0.9629 (7)0.2255 (6)0.5700 (4)0.0113 (8)
O(10)0.0732 (7)0.5777 (6)0.6854 (4)0.0109 (8)
O(11)0.2411 (7)0.9129 (7)0.9994 (3)0.0111 (8)
O(12)0.3462 (6)0.7886 (7)0.1888 (4)0.0095 (8)
O(13)0.9982 (6)0.6683 (6)0.0809 (3)0.0077 (8)
O(14)0.0029 (6)0.0165 (6)0.1830 (3)0.0075 (7)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Dy(1)0.0081 (1)0.0071 (1)0.0026 (1)0.00055 (9)0.00044 (9)0.00098 (9)
Dy(2)0.0061 (1)0.0076 (1)0.0037 (1)0.00091 (9)0.00145 (9)0.00084 (9)
Dy(3)0.0078 (1)0.0126 (1)0.0020 (1)0.0012 (1)0.00071 (9)0.00059 (9)
Dy(4)0.0100 (1)0.0072 (1)0.0054 (1)0.00030 (9)0.00416 (9)0.00193 (9)
Si(1)0.0049 (7)0.0072 (7)0.0024 (6)0.0016 (5)0.0017 (5)0.0014 (5)
Si(2)0.0075 (7)0.0070 (7)0.0039 (7)0.0010 (5)0.0007 (5)0.0026 (5)
Si(3)0.0073 (7)0.0070 (7)0.0050 (7)0.0016 (5)0.0001 (5)0.0016 (5)
Si(4)0.0060 (7)0.0044 (6)0.0063 (7)0.0014 (5)0.0001 (5)0.0005 (5)
O(1)0.006 (2)0.011 (2)0.005 (2)0.003 (1)0.001 (1)0.001 (1)
O(2)0.019 (2)0.007 (2)0.010 (2)0.003 (2)0.002 (2)0.002 (1)
O(3)0.009 (2)0.019 (2)0.002 (2)0.002 (2)0.001 (1)0.002 (1)
O(4)0.011 (2)0.010 (2)0.001 (2)0.004 (1)0.000 (1)0.003 (1)
O(5)0.008 (2)0.014 (2)0.005 (2)0.004 (1)0.001 (1)0.004 (1)
O(6)0.005 (2)0.010 (2)0.014 (2)0.002 (1)0.002 (2)0.006 (2)
O(7)0.013 (2)0.010 (2)0.005 (2)0.002 (2)0.006 (1)0.004 (1)
O(8)0.006 (2)0.016 (2)0.015 (2)0.003 (2)0.000 (2)0.004 (2)
O(9)0.014 (2)0.011 (2)0.008 (2)0.006 (2)0.004 (2)0.001 (1)
O(10)0.017 (2)0.010 (2)0.006 (2)0.005 (2)0.001 (2)0.000 (1)
O(11)0.019 (2)0.010 (2)0.003 (2)0.008 (2)0.006 (2)0.003 (1)
O(12)0.006 (2)0.016 (2)0.007 (2)0.004 (2)0.000 (1)0.000 (1)
O(13)0.006 (2)0.008 (2)0.008 (2)0.006 (1)0.001 (1)0.003 (1)
O(14)0.008 (2)0.006 (2)0.008 (2)0.002 (1)0.001 (1)0.001 (1)
Geometric parameters (Å, º) top
Dy(1)—O(1)2.325 (2)Dy(4)—O(2)vi2.367 (4)
Dy(1)—O(2)2.789 (3)Dy(4)—O(3)vii2.537 (4)
Dy(1)—O(3)i2.343 (1)Dy(4)—O(8)ii2.531 (5)
Dy(1)—O(10)ii2.427 (4)Dy(4)—O(11)viii2.295 (4)
Dy(1)—O(11)ii2.380 (3)Dy(4)—O(12)2.374 (2)
Dy(1)—O(13)2.333 (4)Dy(4)—O(13)2.475 (2)
Dy(1)—O(13)iii2.410 (4)Dy(4)—O(14)ix2.629 (2)
Dy(1)—O(14)i2.336 (4)Si(1)—O(11)x1.602 (4)
Dy(2)—O(2)2.558 (3)Si(1)—O(12)1.610 (3)
Dy(2)—O(5)2.313 (2)Si(1)—O(13)xi1.616 (3)
Dy(2)—O(6)i2.267 (4)Si(1)—O(14)vi1.673 (3)
Dy(2)—O(8)iv2.354 (4)Si(2)—O(1)1.600 (4)
Dy(2)—O(9)2.656 (4)Si(2)—O(2)1.652 (4)
Dy(2)—O(9)v2.571 (4)Si(2)—O(3)1.582 (3)
Dy(2)—O(10)ii2.304 (4)Si(2)—O(4)1.744 (4)
Dy(2)—O(14)i2.304 (4)Si(3)—O(4)1.635 (4)
Dy(3)—O(4)2.429 (4)Si(3)—O(5)1.630 (3)
Dy(3)—O(5)ii2.250 (4)Si(3)—O(6)1.542 (3)
Dy(3)—O(6)vi2.328 (4)Si(3)—O(7)1.688 (4)
Dy(3)—O(8)ii2.381 (1)Si(4)—O(7)1.665 (4)
Dy(3)—O(9)ii2.348 (1)Si(4)—O(8)1.665 (4)
Dy(3)—O(12)2.181 (4)Si(4)—O(9)xi1.588 (3)
Dy(4)—O(1)2.267 (4)Si(4)—O(10)1.630 (4)
O(11)x—Si(1)—O(12)106.8 (3)O(4)—Si(3)—O(6)114.4 (2)
O(11)x—Si(1)—O(13)xi103.1 (2)O(4)—Si(3)—O(7)103.3 (2)
O(11)x—Si(1)—O(14)vi116.8 (2)O(5)—Si(3)—O(6)104.8 (2)
O(12)—Si(1)—O(13)xi113.6 (2)O(5)—Si(3)—O(7)109.0 (2)
O(12)—Si(1)—O(14)vi114.9 (2)O(6)—Si(3)—O(7)109.7 (2)
O(13)xi—Si(1)—O(14)vi101.1 (2)O(7)—Si(4)—O(8)103.2 (2)
O(1)—Si(2)—O(2)107.6 (2)O(7)—Si(4)—O(9)xi107.6 (2)
O(1)—Si(2)—O(3)109.4 (2)O(7)—Si(4)—O(10)110.2 (2)
O(1)—Si(2)—O(4)111.0 (2)O(8)—Si(4)—O(9)xi102.7 (2)
O(2)—Si(2)—O(3)118.8 (3)O(8)—Si(4)—O(10)117.2 (2)
O(2)—Si(2)—O(4)100.6 (2)O(9)xi—Si(4)—O(10)114.8 (3)
O(3)—Si(2)—O(4)109.1 (2)Si(2)—O(4)—Si(3)119.7 (3)
O(4)—Si(3)—O(5)115.7 (2)Si(3)—O(7)—Si(4)131.4 (3)
Symmetry codes: (i) x+1, y, z; (ii) x+1, y+1, z+1; (iii) x+2, y+1, z; (iv) x+1, y, z+1; (v) x+2, y, z+1; (vi) x, y+1, z; (vii) x+1, y+1, z; (viii) x+1, y+2, z+1; (ix) x+1, y+1, z; (x) x, y, z1; (xi) x1, y, z.

Experimental details

Crystal data
Chemical formulaDy2Si2O7
Mr493.17
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)6.6158 (2), 6.6604 (2), 12.0551 (4)
α, β, γ (°)94.373 (2), 90.836 (2), 91.512 (2)
V3)529.39
Z4
Radiation typeMo Kα
µ (mm1)28.45
Crystal size (mm)0.11 × 0.10 × 0.05
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correctionGaussian
(Coppens, Leiserowitz & Rabinovich, 1965)
Tmin, Tmax0.144, 0.380
No. of measured, independent and
observed [I 3σ(I)] reflections
32768, 4470, 3220
Rint0.107
(sin θ/λ)max1)0.809
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.041, 0.98
No. of reflections4470
No. of parameters204
Δρmax, Δρmin (e Å3)4.65, 4.70

Computer programs: COLLECT (Nonius, 1997), SUNY Buffalo DATAP77, SHELXTL PC Siemens, SUNY Buffalo LINEX77, Shape Software ATOMS, ORTEP-3 for Windows.

Selected geometric parameters (Å, º) top
Dy(1)—O(1)2.325 (2)Dy(2)—O(14)i2.304 (4)
Dy(1)—O(2)2.789 (3)Dy(3)—O(4)2.429 (4)
Dy(1)—O(3)i2.343 (1)Dy(3)—O(5)ii2.250 (4)
Dy(1)—O(10)ii2.427 (4)Dy(3)—O(6)vi2.328 (4)
Dy(1)—O(11)ii2.380 (3)Dy(3)—O(8)ii2.381 (1)
Dy(1)—O(13)2.333 (4)Dy(3)—O(9)ii2.348 (1)
Dy(1)—O(13)iii2.410 (4)Dy(3)—O(12)2.181 (4)
Dy(1)—O(14)i2.336 (4)Dy(4)—O(1)2.267 (4)
Dy(2)—O(2)2.558 (3)Dy(4)—O(2)vi2.367 (4)
Dy(2)—O(5)2.313 (2)Dy(4)—O(3)vii2.537 (4)
Dy(2)—O(6)i2.267 (4)Dy(4)—O(8)ii2.531 (5)
Dy(2)—O(8)iv2.354 (4)Dy(4)—O(11)viii2.295 (4)
Dy(2)—O(9)2.656 (4)Dy(4)—O(12)2.374 (2)
Dy(2)—O(9)v2.571 (4)Dy(4)—O(13)2.475 (2)
Dy(2)—O(10)ii2.304 (4)Dy(4)—O(14)ix2.629 (2)
O(11)x—Si(1)—O(12)106.8 (3)O(4)—Si(3)—O(6)114.4 (2)
O(11)x—Si(1)—O(13)xi103.1 (2)O(4)—Si(3)—O(7)103.3 (2)
O(11)x—Si(1)—O(14)vi116.8 (2)O(5)—Si(3)—O(6)104.8 (2)
O(12)—Si(1)—O(13)xi113.6 (2)O(5)—Si(3)—O(7)109.0 (2)
O(12)—Si(1)—O(14)vi114.9 (2)O(6)—Si(3)—O(7)109.7 (2)
O(13)xi—Si(1)—O(14)vi101.1 (2)O(7)—Si(4)—O(8)103.2 (2)
O(1)—Si(2)—O(2)107.6 (2)O(7)—Si(4)—O(9)xi107.6 (2)
O(1)—Si(2)—O(3)109.4 (2)O(7)—Si(4)—O(10)110.2 (2)
O(1)—Si(2)—O(4)111.0 (2)O(8)—Si(4)—O(9)xi102.7 (2)
O(2)—Si(2)—O(3)118.8 (3)O(8)—Si(4)—O(10)117.2 (2)
O(2)—Si(2)—O(4)100.6 (2)O(9)xi—Si(4)—O(10)114.8 (3)
O(3)—Si(2)—O(4)109.1 (2)Si(2)—O(4)—Si(3)119.7 (3)
O(4)—Si(3)—O(5)115.7 (2)Si(3)—O(7)—Si(4)131.4 (3)
Symmetry codes: (i) x+1, y, z; (ii) x+1, y+1, z+1; (iii) x+2, y+1, z; (iv) x+1, y, z+1; (v) x+2, y, z+1; (vi) x, y+1, z; (vii) x+1, y+1, z; (viii) x+1, y+2, z+1; (ix) x+1, y+1, z; (x) x, y, z1; (xi) x1, y, z.
 

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