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inorganic papers

i102

Matthias Weil Cd

3[Si3O9] doi:10.1107/S1600536805015278 Acta Cryst.(2005). E61, i102–i104

Acta Crystallographica Section E

Structure Reports Online

ISSN 1600-5368

Parawollastonite-type Cd

3

[Si

3

O

9

]

Matthias Weil

Institute for Chemical Technologies and Analytics, Division of Structural Chemistry, Vienna University of Technology, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria

Correspondence e-mail: mweil@mail.zserv.tuwien.ac.at

Key indicators

Single-crystal X-ray study

T= 293 K

Mean(Si–O) = 0.002 A˚

Rfactor = 0.023

wRfactor = 0.064

Data-to-parameter ratio = 17.6

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

#2005 International Union of Crystallography

Printed in Great Britain – all rights reserved

Cd3[Si3O9] (tricadmium trisilicate) crystallizes in the

mono-clinic space group P21/c and is isotypic with the mineral

parawollastonite, Ca3[Si3O9]-2M. The structure contains

distorted CdO6 octahedra and SiO4 tetrahedra that are

organized in unbranched dreier single chains with three SiO4tetrahedra in the repeat unit. All atoms occupy general

positions 4e.

Comment

Cadmium silicates are of particular interest because of their properties as host materials for luminescent applications when doped with rare earth or transition metal ions. Recently, some CdSiO3:REphosphors (RE = rare earth) with a long-lasting

phosphorescence upon UV-light excitation were reported (Liu

et al., 2005).

[image:1.610.227.437.359.721.2]

Received 5 May 2005 Accepted 13 May 2005 Online 21 May 2005

Figure 1

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In the system CdO—SiO2, three compounds are known to

exist: the orthosilicate Cd2SiO4 which crystallizes in the

thenardite structure type (Dent Glasser & Glasser, 1964), the oxyorthosilicate Cd3OSiO4 with a unique structure (Eysel,

1970), and the polysilicate CdSiO3for which only powder data

were published (Dent Glasser & Glasser, 1964). In the original work, it was not possible to determine the space group of CdSiO3 unequivocally because the crystals were

poly-synthetically twinned. However, powder data revealed a structural relation to the calcium analogue, CaSiO3. The latter

occurs in different polymorphs with structurally quite different arrangements. The high-temperature phase is a cyclosilicate called -wollastonite or pseudowollastonite. Its structure contains rings of three corner-shared SiO4

tetra-hedra organized in a layered arrangement. Depending on the stacking sequence of the layers, a number of polytypes were reported for pseudowollastonite (Yamanaka & Mori, 1981). The low-temperature phases of calcium polysilicate are made up of unbranched single chains of corner-shared SiO4

tetra-hedra. Two polytypes have been reported for the low-temperature phase, often referred to as-wollastonites. They are distinguished by the symbolsnTandnM, whereTandM

symbolize the triclinic and monoclinic symmetry, andn indi-cates the number of subcells. The polytype 1Tis also named wollastonite whereas the polytype 2M is a synonym for parawollastonite (Trojer, 1968; Hesse, 1984). For all poly-morphs, the chemical formulae CaSiO3, Ca3(SiO3)3 or

Ca3[Si3O9] are reported in the literature.

Although it was reported that cadmium polysilicate can occur in different polytypes (Dent Glasser & Glasser, 1964), only the form that is isotypic with parawollastonite was obtained during the present investigation. In accordance with the nomenclature of condensed silicates given by Liebau (1985), the formula of the title compound is written as Cd3[Si3O9].

The Cd3[Si3O9] structure differs only slightly from that of

the isotypic Ca phase (Hesse, 1984), mainly in changes in the Cd—O distances versus the Ca—O distances resulting from the different ionic radii (Shannon, 1976) of 0.95 (Cd2+; CN = 6) and 1.00 A˚ (Ca2+; CN = 6), respectively.

The three independent Cd atoms are each surrounded by six O atoms, forming distorted CdO6 octahedra which are

arranged in slabs parallel to [010]. Three such slabs constitute

ribbons which are separated from each other by unbranched silicate chains that are formed by corner-sharing SiO4

tetra-hedra (Fig. 1). The silicate chains have a repeating period of three SiO4 tetrahedra (Fig. 2) which corresponds with the

length of the baxis. According to Liebau’s (1985) notation, Cd3[Si3O9] is a dreier single chain polysilicate.

The mean Cd—O distances of 2.326 (Cd1), 2.333 (Cd2) and 2.341 A˚ (Cd3) are slightly shorter than the corresponding mean Ca—O distances of 2.385 (Ca1), 2.378 (Ca2) and 2.385 A˚ (Ca3), whereas the mean Si—O distances in Cd3[Si3O9] and

Ca3[Si3O9] are virtually the same,viz. 1.620, 1.627 and 1.635 A˚

in the Cd compoundversus1.620, 1.617 and 1.630 A˚ in the Ca compound. The O—Si—O angles of the silicate chains are very similar in both isotypic structures and are in the range 102.06 (9)–122.12 (10)in the Cd compoundversus102.5 (1)– 122.0 (1)in the Ca compound.

Experimental

CdCO3(Merck, p. A.) and high-surface silica (Degussa–Hu¨ls) were

mixed in the stoichiometric ratio 2:1 and slowly heated in a platinum crucible to 1023 K for 24 h. X-ray powder diffraction of the

poly-crystalline material revealed a mixture of Cd2SiO4(Dent Glasser &

Glasser, 1964) and Cd3[Si3O9]. The mixture was then heated to

1473 K, left at that temperature for 2 h and cooled slowly to 1173 K at

a rate of 4 K h1. The furnace was then shut down. After cooling to

room temperature, the colourless melt was crushed and a plate-like single-crystal was used for the data collection. X-ray powder

diffraction of the final product yielded Cd3[Si3O9], isotypic with

Ca3[Si3O9]-2M, and only minor amounts of Cd2SiO4.

Crystal data

Cd3[Si3O9]

Mr= 565.47 Monoclinic,P21=c

a= 6.9463 (8) A˚

b= 7.2563 (9) A˚

c= 15.0697 (18) A˚

= 94.791 (2) V= 756.93 (16) A˚3

Z= 4

Dx= 4.962 Mg m3 MoKradiation Cell parameters from 4479

reflections

= 2.7–31.2 = 8.86 mm1

T= 293 (2) K Plate, colourless 0.260.140.02 mm

Data collection

Bruker SMART APEX CCD diffractometer

!scans

Absorption correction: multi-scan (SADABS; Bruker, 2002)

Tmin= 0.203,Tmax= 0.816

8622 measured reflections

2412 independent reflections 1980 reflections withI> 2(I)

Rint= 0.037

max= 31.2

h=8!9

k=10!10

l=21!19

Refinement

Refinement onF2

R[F2> 2(F2)] = 0.024

wR(F2) = 0.064

S= 1.07 2412 reflections 137 parameters

w= 1/[2(Fo2) + (0.0215P)2

+ 1.0847P]

whereP= (Fo2+ 2Fc2)/3

(/)max= 0.001

max= 1.60 e A˚

3

min=1.38 e A˚

3

Extinction correction:SHELXL97

Extinction coefficient: 0.00358 (19)

inorganic papers

Acta Cryst.(2005). E61, i102–i104 Matthias Weil Cd

[image:2.610.44.298.71.162.2]

3[Si3O9]

i103

Figure 2

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[image:3.610.44.298.120.360.2]

Table 1

Selected geometric parameters (A˚ ,).

Cd1—O6 2.272 (2) Cd1—O1i 2.3045 (18) Cd1—O9ii 2.317 (2) Cd1—O2iii 2.3214 (19) Cd1—O1 2.3519 (19) Cd1—O2 2.3869 (19) Cd2—O4iv

2.1681 (17) Cd2—O3 2.2113 (17) Cd2—O1i 2.260 (2) Cd2—O7v

2.3939 (17) Cd2—O6 2.4538 (18) Cd2—O9v 2.5102 (18) Cd3—O4vi 2.2262 (17) Cd3—O2iii 2.249 (2) Cd3—O3 2.3073 (17)

Cd3—O8 2.3743 (16) Cd3—O6 2.4293 (18) Cd3—O9vii

2.4573 (18) Si1—O3viii

1.592 (2) Si1—O1 1.620 (2) Si1—O5 1.6219 (15) Si1—O7 1.6447 (17) Si2—O4 1.602 (2) Si2—O2 1.612 (2) Si2—O5 1.6158 (15) Si2—O8v

1.6399 (17) Si3—O6 1.599 (2) Si3—O9 1.605 (2) Si3—O7v

1.6529 (16) Si3—O8 1.6611 (16) O3viii

—Si1—O1 115.83 (11) O3viii

—Si1—O5 107.63 (9) O1—Si1—O5 108.44 (9) O3viii

—Si1—O7 114.32 (10) O1—Si1—O7 107.54 (10) O5—Si1—O7 102.06 (9) O4—Si2—O2 115.78 (11) O4—Si2—O5 106.92 (9) O2—Si2—O5 109.09 (9) O4—Si2—O8v 113.60 (10) O2—Si2—O8v

107.89 (10)

O5—Si2—O8v

102.69 (9) O6—Si3—O9 122.12 (10) O6—Si3—O7v 104.20 (9) O9—Si3—O7v

111.27 (9) O6—Si3—O8 103.48 (9) O9—Si3—O8 111.02 (9) O7v

—Si3—O8 102.80 (9) Si2—O5—Si1 148.03 (13) Si1—O7—Si3vii

139.89 (11) Si2vii—O8—Si3 140.61 (11)

Symmetry codes: (i) x;1

2þy;12z; (ii) x1;y;z; (iii) x;y12;12z; (iv)

x;3 2y;z

1

2; (v) 1x; 1 2þy;

1

2z; (vi) x; 1 2y;z

1

2; (vii) 1x;y 1 2;

1 2z; (viii)

x;1 2y;

1 2þz.

The structure was initially refined in space groupP21/awith the

atomic coordinates of the isotypic compound Ca3[Si3O9]-2M

(para-wollastonite; Hesse, 1984) as starting parameters. For the present

refinement, the standard setting inP21/cwas used and the structural

data were standardized using the program STRUCTURE-TIDY

(Gelato & Parthe´, 1987). The highest peak in the final Fourier map is

0.81 A˚ from atom Cd1 and the deepest hole is 1.64 A˚ from O8.

Data collection:SMART(Bruker, 2002); cell refinement:SAINT

(Bruker, 2002); data reduction:SAINT; method used to solve

struc-ture: coordinates taken from the isotypic Ca compound; program(s)

used to refine structure: SHELXL97 (Sheldrick, 1997); molecular

graphics:ATOMS(Dowty, 2004); software used to prepare material

for publication:SHELXL97.

References

Bruker (2002).SADABS,SMARTandSAINT.Bruker AXS Inc., Madison, Wisconsin, USA.

Dent Glasser, L. S. & Glasser, F. P. (1964).Inorg. Chem.3, 1228–1230. Dowty, E. (2004).ATOMS for Windows. Version 6.1. Shape Software, 521

Hidden Valley Road, Kingsport, TN 37663, USA. Eysel, W. (1970).Neues Jahrb. Mineral.Monatsh.pp. 534–547. Gelato, L. M. & Parthe´, E. (1987).J. Appl Cryst.20, 139–143. Hesse, K. F. (1984).Z. Kristallogr.168, 93–98.

Liebau, F. (1985).Structural Chemistry of Silicates: Structure, Bonding and Classification. Berlin: Springer-Verlag.

Liu, Y., Lei, B. & Shi, C. (2005).Chem. Mater.17, 2108–2113. Shannon, R. D. (1976).Acta Cryst.A32, 751–767.

Sheldrick, G. M. (1997).SHELXL97. University of Go¨ttingen, Germany. Trojer, F. (1968).Z. Kristallogr.127, 291–308.

Yamanaka, T. & Mori, H. (1981).Acta Cryst.B37, 1010–1027.

inorganic papers

i104

Matthias Weil Cd

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supporting information

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Acta Cryst. (2005). E61, i102–i104

supporting information

Acta Cryst. (2005). E61, i102–i104 [https://doi.org/10.1107/S1600536805015278]

Parawollastonite-type Cd

3

[Si

3

O

9

]

Matthias Weil

tricadmium trisilicate

Crystal data Cd3[Si3O9]

Mr = 565.47 Monoclinic, P21/c

Hall symbol: -P 2ybc a = 6.9463 (8) Å b = 7.2563 (9) Å c = 15.0697 (18) Å β = 94.791 (2)° V = 756.93 (16) Å3

Z = 4

F(000) = 1032 Dx = 4.962 Mg m−3

Mo radiation, λ = 0.71073 Å Cell parameters from 4479 reflections θ = 2.7–31.2°

µ = 8.86 mm−1

T = 293 K Plate, colourless 0.26 × 0.14 × 0.02 mm

Data collection Bruker APEX CCD

diffractometer

Radiation source: fine-focus sealed tube Graphite monochromator

ω scans

Absorption correction: multi-scan (SADABS; Bruker, 2002) Tmin = 0.203, Tmax = 0.816

8622 measured reflections 2412 independent reflections 1980 reflections with I > 2σ(I) Rint = 0.037

θmax = 31.2°, θmin = 2.7°

h = −8→9 k = −10→10 l = −21→19

Refinement Refinement on F2

Least-squares matrix: full R[F2 > 2σ(F2)] = 0.024

wR(F2) = 0.064

S = 1.07 2412 reflections 137 parameters 0 restraints

Primary atom site location: isomorphous structure methods

w = 1/[σ2(F

o2) + (0.0215P)2 + 1.0847P]

where P = (Fo2 + 2Fc2)/3

(Δ/σ)max = 0.001

Δρmax = 1.60 e Å−3

Δρmin = −1.38 e Å−3

Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4

Extinction coefficient: 0.00358 (19)

Special details

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supporting information

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Acta Cryst. (2005). E61, i102–i104

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)

x y z Uiso*/Ueq

Cd1 0.01235 (2) 0.37607 (2) 0.248498 (10) 0.00866 (7) Cd2 0.24957 (3) 0.62788 (2) 0.098674 (12) 0.00993 (7) Cd3 0.25370 (2) 0.11992 (2) 0.101523 (12) 0.00989 (7) Si1 0.23852 (9) 0.16124 (8) 0.41008 (4) 0.00760 (12) Si2 0.23940 (9) 0.59016 (8) 0.41056 (4) 0.00734 (12) Si3 0.54611 (9) 0.37667 (7) 0.19864 (4) 0.00723 (12) O1 0.0431 (3) 0.1232 (2) 0.34626 (15) 0.0103 (4) O2 0.0428 (3) 0.6305 (2) 0.34907 (15) 0.0109 (4) O3 0.2259 (3) 0.3799 (2) 0.01320 (14) 0.0131 (4) O4 0.2314 (3) 0.6289 (2) 0.51484 (14) 0.0132 (4) O5 0.2977 (3) 0.37608 (19) 0.40041 (12) 0.0137 (3) O6 0.3173 (3) 0.3745 (2) 0.20452 (14) 0.0106 (4) O7 0.4167 (2) 0.0551 (2) 0.36594 (11) 0.0121 (3) O8 0.5842 (2) 0.1982 (2) 0.13334 (11) 0.0120 (3) O9 0.6954 (3) 0.3759 (2) 0.28588 (13) 0.0100 (4)

Atomic displacement parameters (Å2)

U11 U22 U33 U12 U13 U23

Cd1 0.00874 (11) 0.00846 (11) 0.00886 (12) −0.00002 (4) 0.00115 (8) 0.00004 (4) Cd2 0.01053 (11) 0.00889 (10) 0.01051 (11) 0.00156 (5) 0.00171 (7) 0.00156 (5) Cd3 0.00982 (11) 0.00962 (10) 0.01035 (11) −0.00154 (5) 0.00142 (7) −0.00174 (5) Si1 0.0080 (3) 0.0077 (2) 0.0070 (3) 0.00052 (19) −0.0003 (2) −0.0002 (2) Si2 0.0082 (3) 0.0073 (2) 0.0064 (3) −0.00049 (19) −0.0005 (2) −0.00004 (19) Si3 0.0064 (3) 0.0077 (2) 0.0075 (3) −0.00001 (18) 0.0000 (2) −0.00018 (19) O1 0.0089 (9) 0.0137 (9) 0.0084 (9) −0.0008 (6) 0.0005 (7) −0.0009 (6) O2 0.0090 (9) 0.0141 (9) 0.0093 (9) −0.0012 (6) 0.0000 (7) 0.0020 (6) O3 0.0202 (10) 0.0125 (8) 0.0067 (9) 0.0006 (6) 0.0010 (7) −0.0011 (6) O4 0.0235 (11) 0.0107 (8) 0.0053 (8) −0.0003 (6) 0.0012 (7) −0.0007 (6) O5 0.0182 (8) 0.0067 (7) 0.0165 (8) 0.0005 (5) 0.0044 (6) 0.0000 (5) O6 0.0058 (8) 0.0162 (8) 0.0099 (8) −0.0009 (6) 0.0004 (6) −0.0008 (6) O7 0.0110 (7) 0.0100 (6) 0.0150 (8) 0.0020 (5) −0.0008 (6) −0.0044 (6) O8 0.0105 (8) 0.0104 (7) 0.0149 (8) 0.0017 (5) 0.0001 (6) −0.0047 (6) O9 0.0077 (8) 0.0147 (8) 0.0074 (8) 0.0012 (6) −0.0018 (6) 0.0000 (6)

Geometric parameters (Å, º)

Cd1—O6 2.272 (2) Si1—O1 1.620 (2) Cd1—O1i 2.3045 (18) Si1—O5 1.6219 (15)

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Acta Cryst. (2005). E61, i102–i104

Cd1—O2iii 2.3214 (19) Si2—O4 1.602 (2)

Cd1—O1 2.3519 (19) Si2—O2 1.612 (2) Cd1—O2 2.3869 (19) Si2—O5 1.6158 (15) Cd1—O5 2.9000 (18) Si2—O8v 1.6399 (17)

Cd1—Cd2 3.4312 (3) Si3—O6 1.599 (2) Cd1—Cd3 3.4338 (3) Si3—O9 1.605 (2) Cd2—O4iv 2.1681 (17) Si3—O7v 1.6529 (16)

Cd2—O3 2.2113 (17) Si3—O8 1.6611 (16) Cd2—O1i 2.260 (2) O1—Cd2iii 2.260 (2)

Cd2—O7v 2.3939 (17) O1—Cd1iii 2.3045 (18)

Cd2—O6 2.4538 (18) O2—Cd3i 2.249 (2)

Cd2—O9v 2.5102 (18) O2—Cd1i 2.3214 (19)

Cd2—Si3 3.0524 (6) O3—Si1vi 1.592 (2)

Cd3—O4vi 2.2262 (17) O4—Cd2ix 2.1681 (17)

Cd3—O2iii 2.249 (2) O4—Cd3viii 2.2262 (17)

Cd3—O3 2.3073 (17) O7—Si3vii 1.6529 (16)

Cd3—O8 2.3743 (16) O7—Cd2vii 2.3939 (17)

Cd3—O6 2.4293 (18) O8—Si2vii 1.6399 (17)

Cd3—O9vii 2.4573 (18) O9—Cd1x 2.317 (2)

Cd3—Si3 3.0400 (6) O9—Cd3v 2.4573 (18)

Si1—O3viii 1.592 (2) O9—Cd2vii 2.5102 (18)

O6—Cd1—O1i 86.27 (7) O5—Si1—O7 102.06 (9)

O6—Cd1—O9ii 177.10 (5) O4—Si2—O2 115.78 (11)

O1i—Cd1—O9ii 92.17 (7) O4—Si2—O5 106.92 (9)

O6—Cd1—O2iii 85.40 (7) O2—Si2—O5 109.09 (9)

O1i—Cd1—O2iii 101.21 (8) O4—Si2—O8v 113.60 (10)

O9ii—Cd1—O2iii 92.51 (7) O2—Si2—O8v 107.89 (10)

O6—Cd1—O1 98.08 (7) O5—Si2—O8v 102.69 (9)

O1i—Cd1—O1 175.573 (9) O6—Si3—O9 122.12 (10)

O9ii—Cd1—O1 83.45 (7) O6—Si3—O7v 104.20 (9)

O2iii—Cd1—O1 78.43 (9) O9—Si3—O7v 111.27 (9)

O6—Cd1—O2 98.85 (7) O6—Si3—O8 103.48 (9) O1i—Cd1—O2 78.05 (9) O9—Si3—O8 111.02 (9)

O9ii—Cd1—O2 83.19 (7) O7v—Si3—O8 102.80 (9)

O2iii—Cd1—O2 175.598 (11) Si1—O1—Cd2iii 120.95 (12)

O1—Cd1—O2 101.96 (8) Si1—O1—Cd1iii 126.08 (11)

O4iv—Cd2—O3 108.98 (9) Cd2iii—O1—Cd1iii 97.49 (8)

O4iv—Cd2—O1i 102.47 (8) Si1—O1—Cd1 105.46 (9)

O3—Cd2—O1i 100.15 (8) Cd2iii—O1—Cd1 100.41 (8)

O4iv—Cd2—O7v 108.52 (7) Cd1iii—O1—Cd1 102.54 (9)

O3—Cd2—O7v 88.49 (7) Si2—O2—Cd3i 123.97 (13)

O1i—Cd2—O7v 143.05 (7) Si2—O2—Cd1i 126.20 (11)

O4iv—Cd2—O6 170.92 (7) Cd3i—O2—Cd1i 97.40 (8)

O3—Cd2—O6 76.68 (7) Si2—O2—Cd1 104.50 (9) O1i—Cd2—O6 83.08 (7) Cd3i—O2—Cd1 98.56 (7)

O7v—Cd2—O6 63.92 (6) Cd1i—O2—Cd1 100.98 (9)

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Acta Cryst. (2005). E61, i102–i104

O3—Cd2—O9v 170.71 (7) Si1vi—O3—Cd3 113.65 (8)

O1i—Cd2—O9v 81.13 (7) Cd2—O3—Cd3 109.31 (9)

O7v—Cd2—O9v 85.14 (6) Si2—O4—Cd2ix 135.17 (10)

O6—Cd2—O9v 94.42 (7) Si2—O4—Cd3viii 115.28 (8)

O4vi—Cd3—O2iii 101.60 (8) Cd2ix—O4—Cd3viii 108.69 (9)

O4vi—Cd3—O3 109.03 (8) Si2—O5—Si1 148.03 (13)

O2iii—Cd3—O3 97.36 (7) Si3—O6—Cd1 166.24 (13)

O4vi—Cd3—O8 109.34 (7) Si3—O6—Cd3 95.78 (9)

O2iii—Cd3—O8 145.24 (7) Cd1—O6—Cd3 93.78 (6)

O3—Cd3—O8 87.36 (7) Si3—O6—Cd2 95.40 (9) O4vi—Cd3—O6 172.55 (7) Cd1—O6—Cd2 93.04 (6)

O2iii—Cd3—O6 83.41 (7) Cd3—O6—Cd2 98.03 (7)

O3—Cd3—O6 75.46 (7) Si1—O7—Si3vii 139.89 (11)

O8—Cd3—O6 64.41 (6) Si1—O7—Cd2vii 123.65 (8)

O4vi—Cd3—O9vii 79.62 (6) Si3vii—O7—Cd2vii 96.20 (8)

O2iii—Cd3—O9vii 83.04 (7) Si2vii—O8—Si3 140.61 (11)

O3—Cd3—O9vii 170.97 (7) Si2vii—O8—Cd3 123.15 (8)

O8—Cd3—O9vii 87.25 (6) Si3—O8—Cd3 96.15 (7)

O6—Cd3—O9vii 95.66 (7) Si3—O9—Cd1x 111.27 (11)

O3viii—Si1—O1 115.83 (11) Si3—O9—Cd3v 127.52 (9)

O3viii—Si1—O5 107.63 (9) Cd1x—O9—Cd3v 94.75 (6)

O1—Si1—O5 108.44 (9) Si3—O9—Cd2vii 128.35 (9)

O3viii—Si1—O7 114.32 (10) Cd1x—O9—Cd2vii 94.37 (6)

O1—Si1—O7 107.54 (10) Cd3v—O9—Cd2vii 91.91 (7)

Figure

Figure 1
Figure 2
Table 1Selected geometric parameters (A˚ , �).

References

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Inspired by Wang and Jiang ( 2016b ), we in- troduce a gated self-matching network, illustrated in Figure 1 , an end-to-end neural network model for reading comprehension and

Blanco and Zaragoza (2010) study the informa- tion retrieval problem of finding support sentences which explain the relationship between a query and an entity, which is similar to

remove health expenditures from the model (table 3, column 5), which are insignificant anyway, military expenditures become significant at the 10% significance level, the

CDUS should be used as a first modality in evaluation of patients of PAD especially where low grade stenosis is anticipated, patients prone for significant vascular calcification

Long-term sustainability of human and non-human life can be achieved only by creating an entirely new economy that eschews the current economy’s pursuit of continuous growth and