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Comptes Rendus

Hydrothermal synthesis, crystal structure, thermal behaviour, IR and Raman spectroscopy of Na3Y(CO3)3 ˙6 H2O
Comptes Rendus. Chimie, Volume 7 (2004) no. 6-7, pp. 661-668.

Résumés

A new sodium yttrium carbonate hydrate, Na3Y(CO3)3 ˙6 H2O, is prepared by hydrothermal synthesis and characterized by single crystal X-ray diffraction, thermal analysis, IR and Raman spectroscopy. Na3Y(CO3)3 ˙6 H2O crystallizes in the hexagonal system, space group P63 ; a = 11.347(5) Å, c = 5.935(5) Å; V = 661.8(5) Å3; Z = 2. Refinements yield R(F2) = 0.058 and Rw(F2) = 0.161 for 692 unique reflections. The structure is built up from [YO3+3+3] polyhedra surrounded by [NaO6] octahedra. Carbonate groups form infinite layers at z ≈ 0.175 and z ≈ 0.675. Dehydration of Na3Y(CO3)3 ˙6 H2O yields an amorphous carbonate. .

Un nouveau carbonate d'yttrium et de sodium hydraté, Na3Y(CO3)3 ˙6 H2O, est préparé par synthèse hydrothermale et caractérisé par diffraction des rayons X, analyse thermique et spectroscopies d'absorption IR et de diffusion Raman. Na3Y(CO3)3 ˙6 H2O cristallise dans le système hexagonal, groupe spatial P63 ; a = 11,347(5) Å, c = 5,935(5) Å; V = 661.8(5) Å3; Z = 2. Les affinements conduisent aux facteurs de confiance R(F2) = 0,058 et Rw(F2) = 0,161 pour 692 réflexions uniques. La structure est bâtie à partir de polyèdres [YO3+3+3] entourés par six octaèdres [NaO6]. Les groupements carbonate forment des couches infinies à z ≈ 0.175 et z ≈ 0.675. La déshydratation de Na3Y(CO3)3 ˙6 H2O conduit à un carbonate amorphe. .

Métadonnées
Reçu le :
Accepté le :
Publié le :
DOI : 10.1016/j.crci.2004.03.007
Keywords: Carbonate, X-ray diffraction, IR, Raman
Mots clés : Carbonate, Diffraction X, IR, Raman

Amor Ben Ali 1, 2 ; Mohamed Osman Awaleh 1 ; Marc Leblanc 1 ; Leila Samia Smiri 2 ; Vincent Maisonneuve 1 ; Sylvie Houlbert 3

1 Laboratoire des oxydes et fluorures, UMR 6010 CNRS, faculté des sciences, université du Maine, av. Olivier-Messiaen, 72085 Le Mans cedex 9, France
2 Laboratoire de chimie inorganique et structurale, faculté des sciences de Bizerte, 7021 Jarzouna, Tunisie
3 Laboratoire de physique de l'état condensé, UMR 6087 CNRS, faculté des sciences, université du Maine, av. Olivier-Messiaen, 72085 Le Mans cedex 9, France
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     author = {Amor Ben Ali and Mohamed Osman Awaleh and Marc Leblanc and Leila Samia Smiri and Vincent Maisonneuve and Sylvie Houlbert},
     title = {Hydrothermal synthesis, crystal structure, thermal behaviour, {IR} and {Raman} spectroscopy of {Na\protect\textsubscript{3}Y(CO\protect\textsubscript{3})\protect\textsubscript{3}}$ \dot{\mathrm{~}}$6 {H\protect\textsubscript{2}O}},
     journal = {Comptes Rendus. Chimie},
     pages = {661--668},
     publisher = {Elsevier},
     volume = {7},
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%A Leila Samia Smiri
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Amor Ben Ali; Mohamed Osman Awaleh; Marc Leblanc; Leila Samia Smiri; Vincent Maisonneuve; Sylvie Houlbert. Hydrothermal synthesis, crystal structure, thermal behaviour, IR and Raman spectroscopy of Na3Y(CO3)3$ \dot{\mathrm{ }}$6 H2O. Comptes Rendus. Chimie, Volume 7 (2004) no. 6-7, pp. 661-668. doi : 10.1016/j.crci.2004.03.007. https://comptes-rendus.academie-sciences.fr/chimie/articles/10.1016/j.crci.2004.03.007/

Version originale du texte intégral

1 Introduction

During the investigation of ternary diagrams Na2CO3–YbF3–H2O [1] and Na2CO3–YF3–H2O [2] at T = 190 °C, we have found four new fluoride carbonate families, Na2REE(CO3)2F (REE = Y, Yb), Na3Y(CO3)2F2, Na3Yb(CO3)2F2, Na4Y(CO3)2F3 ˙H2O, together with one carbonate hydrate Na5Yb(CO3)4 ˙2 H2O [3]. At high carbonate concentration and T = 220 °C, two other carbonates appear, Na5Y(CO3)4 [3] and Na3Y(CO3)3 ˙6 H2O (this publication). Five sodium yttrium carbonates have been previously reported: four minerals, NaY(CO3)F2 horvathite [4], Na3(Y,REE)(CO3)3 ˙3 H2O shomiokite [5], Na(Y,REE)(HCO3)(OH)3 ˙4 H2O thomasclarkite [6], NaY(CO3)2 ˙6 H2O adamsite [7,8], and one synthetic phase, NaY(CO3)2 [9].

In this paper, the synthesis, the crystal structure, the thermal behaviour and the vibrational analysis of Na3Y(CO3)3 ˙6 H2O are reported. A structural relationship is found with Na3(Y,REE)(CO3)3 ˙3 H2O shomiokite.

2 Experimental

Crystals of Na3Y(CO3)3 ˙6 H2O grow in a Teflon lined Parr autoclave at 220 °C during 48 h from Na2CO3/YF3/H2O in the molar ratio 25:1:55. They are washed with water and acetone and dried in air.

Volume weight was measured with a pycnometer AccuPyc 1330 V3.03. The experimental value ρexp = 2.25 (5) g cm–3 is consistent with the calculated value ρcalc = 2.24 g cm–3.

Thermal analyses were performed with a DTA–TGA TA Instrument 2960 (heating rate 10 °C min–1, argon atmosphere) in the temperature range 25–1000 °C.

Single crystal diffraction data were obtained on a Siemens AED2 four-circle diffractometer. The conditions of intensity measurement are reported in Table 1.

Table 1

Crystallographic data of Na3Y(CO3)3 ˙6 H2O

Crystal systemHexagonal
Space groupP63 (No. 173)
a (Å)11.347(5)
c (Å)5.935(5)
V3), Z661.8(5), 2
μ(Mo Kα) (mm-1)4.62
ρcalc(g cm-3)2.24
ρexp(g cm-3)2.25(5)
Temperature (K)298
Four-circle diffractometerSiemens AED2
Monochromatorgraphite
2θ range (°)2–55
(hkl) limits (two sets)|h| ≤ 12; |k| ≤ 14; |l| ≤ 7
Scan modeω–2θ
Absorption correctionGaussian
Reflections measured/unique/used (I > 2 σ(I))1132/983/692
Parameters refined (on F2)75
R(int)/R(sigma)0.07/0.11
a R/Rw0.058/0.161
Goodness of fit1.05
Weighting scheme (P = [F02 + 2 Fc2]/3)1/[σ2(F02) + (0.08 P)2]
Secondary extinction coefficient0.5(6) × 10-5

a R = Σ||Fo| – |Fc||/Σ|Fo| ; Rw = Σ[w(|Fo|2 – |Fc|2)2w(Fo2)2]1/2.

The infrared spectrum of Na3Y(CO3)3 ˙6 H2O was obtained using a Bomem Michelson MB120 FTIR spectrometer with a diamond-anvil cell as a microsampling device. Infrared data were collected in the range 650–4000 cm–1. Spectral resolution was 4 cm–1.

The Raman scattering study was performed in the backscattering geometry, under microscope (×50 objective), on a powder (without polarisation analysis). The spectrum was collected with a T64000 Jobin-Yvon multichannel spectrometer (in triple substractive configuration with 1800 lines/mm grating), using the 514.5 nm radiation of an argon–krypton laser as excitation, with 8 mW power on the sample in the range 40–4000 cm–1. The typical spectral resolution was better than 0.7 cm–1.

3 Structure determination

The systematic existing conditions of reflections 000l (l =2n) led to the P63 and P63/m space groups. Owing to a positive second harmonic generation test, the non-centrosymmetric P63 space group was chosen. The positions of yttrium atoms were obtained using the Patterson method (option PATT in SHELXS-86 [10]). Analysis of successive Fourier difference maps allowed the location of the remaining atoms. Na, C, and O were distinguished from distance criteria and from valence bond analysis. The refinement (SHELXL-97 [11]) of the atomic coordinates and anisotropic displacement parameters after absorption correction (Gauss method in SHELX-76 [12]), decreased the reliability factors to R = 0.058 and Rw = 0.161.

The final atomic coordinates with isotropic displacement parameters and bond valence analysis, the anisotropic displacement parameters and selected bond distances and angles are given in Tables 2, 3 and 4, respectively.

Table 2

Atomic coordinates, equivalent isotropic displacement parameters and valence bond sums in Na3Y(CO3)3 ˙6 H2O

AtomSitexyzBeq2)ΣsaΣsexpected
Y2b1/32/30.9023(4)1.31(4)3.123
Na6c0.3749(5)0.3634(5)0.6788(8)2.12(8)1.11
C6c0.120(1)0.436(1)0.676(2)1.6(2)b3.94
O(1)6c0.0313(9)0.3382(7)0.563(1)1.8(1)1.72
O(2)6c0.2505(9)0.4869(9)0.634(2)1.8(2)1.82
O(3)6c0.0914(8)0.4929(8)0.841(1)1.8(1)1.92
Ow(1)6c0.158(1)0.179(1)0.555(3)6.6(4)
Ow(2)6c0.493(1)0.216(1)0.674(2)2.3(2)
H(11)6c0.08(1)0.10(1)0.47(2)4.0
H(12)6c0.12(2)0.25(2)0.52(2)4.0
H(21)6c0.47(1)0.20(1)0.85(3)4.0
H(22)6c0.54(2)0.17(2)0.68(3)4.0

a The results refer to the equation s = exp[(r0r)/0.37] with r0 = 2.014, 1.80 and 1.39 for Y–O, Na–O, and C–O, respectively.

b Isotropic displacement.

Table 3

Anisotropic displacement parameters in Na3Y(CO3)3 ˙6 H2O

AtomeU11U22U33U23U13U12
Y0.0157(5)U110.0184(7)00U11/2
Na0.028(3)0.030(3)0.025(2)0.006(2)0.006(2)0.016(2)
O(1)0.023(4)0.014(4)0.028(4)–0.014(3)–0.003(4)0.007(3)
O(2)0.020(4)0.021(4)0.030(5)–0.006(4)–0.006(4)0.010(4)
O(3)0.025(4)0.025(4)0.021(4)–0.005(3)–0.003(3)0.013(3)
Ow(1)0.046(7)0.044(7)0.16(1)–0.018(8)–0.023(8)0.025(6)
Ow(2)0.030(5)0.033(5)0.025(4)–0.006(4)0.002(4)0.017(4)
Table 4

Selected inter-atomic distances (Å) and angles (°) in Na3Y(CO3)3 ˙6 H2O

3 × Y–Ow(2)2.37(1)Na–O(3)2.329(9)
3 × Y–O(2)2.380(9)Na–O(1)2.347(9)
3 × Y–O(3)2.479(8)Na–Ow(1)2.41(1)
Na–O(2)2.45(1)
Na–O(3)2.508(9)
Na–Ow(2)2.61(1)
<Y–O>2.41<Na–O>2.44
C(1)–O(1)1.26(1)O(2)–C–O(3)116(1)
C(1)–O(2)1.30(1)O(1)–C–O(2)121(1)
C(1)–O(3)1.31(1)O(1)–C–O(3)123(1)
<C–O>1.29<O–C–O>120
Ow(1)–H(11)1.0(1)Ow(2)–H(22)1.1(2)
Ow(1)–H(12)1.1(1)Ow(2)–H(21)0.9(2)

4 Structure description

In the structure of Na3Y(CO3)3 ˙6H2O, yttrium atoms are surrounded by six oxygen atoms and three water molecules to form tricaped triangular prisms [YO3+3(H2O)3] similar to that found in shomiokite (Fig. 1 left and right). The mean Y–O distance, 2.41 Å, is very close to that encountered in Na3(Y,REE)(CO3)3 ˙3 H2O shomiokite (2.42 Å) and NaY(CO3)2 ˙6 H2O adamsite (2.42 Å). Sodium cations form distorted [NaO4(H2O)2] octahedra. Na–O distances range from 2.33 to 2.61 Å, with an average of 2.44 Å; these values and the coordination number are comparable to that found in Na3Y(CO3)3 ˙3 H2O and NaY(CO3)2 ˙6 H2O. The Ow(2) atom is bonded to one Y3+ (2.37 Å) and 1Na+ (2.61 Å). Ow(1) is only bonded to one Na+ (2.41 Å); consequently, the Ow(1) atom presents an abnormally high anisotropic displacement parameter (U33 = 0.16(1)).

Fig. 1

[YO3+3+3] and [(Y, Ln)O3+3+3] polyhedra in Na3Y(CO3)3 ˙6 H2O (left) and shomiokite Na3(Y,Ln)(CO3)3 ˙3 H2O (right).

The distorted [NaO4(H2O)2] octahedra build infinite [001] corrugated chains [NaO4O2/2] (Fig. 2, left). Each [YO3+3(H2O)3] polyhedron is connected by edges to six [NaO4(H2O)2] octahedra that belong to three independent [NaO4O2/2] chains (Fig. 2 right). Two adjacent [YO3+3(H2O)3] polyhedra located at z = 0.4 and z = 0.9 share a unique [NaO4O2/2] chain. Six chains form cavities in which hydrogen atoms of water molecules point (Fig. 3). Water molecules H2Ow(1) and H2Ow(2) establish hydrogen bonds with O(1) and O(2), respectively (Table 5).

Fig. 2

[001] chains [NaO4O2/2] (left) and connection of [YO3+3(H2O)3] polyhedra (yellow) and [NaO4(H2O)2] octahedra (violet) in Na3Y(CO3)3 ˙6 H2O (right).

Fig. 3

[0001] projection of Na3Y(CO3)3 ˙6 H2O.

Table 5

Hydrogen bonds in Na3Y(CO3)3 ˙6 H2O

O–H ˙ ˙ ˙OH ˙ ˙ ˙O (Å)Ow ˙ ˙ ˙O (Å)OwHO (°)
Ow(1)–H(12) ˙ ˙ ˙O(1)1.82.8172
Ow(1)–H(12) ˙ ˙ ˙O(2)2.53.2160
Ow(2)–H(21) ˙ ˙ ˙O(2)1.92.7174
Ow(2)–H(22) ˙ ˙ ˙O(1)2.32.6155
Ow(2)–H(22) ˙ ˙ ˙O(3)2.13.0164

Carbon atoms lie at z = 0.176 and z = 0.676 (Fig. 4); with O(1), O(2) and O(3) atoms, they form infinite layers of carbonate groups in which the shortest C–C distance is 4.37 Å. In one layer, it is remarkable that carbon atoms are approximately located at the nodes of a two-dimensional hexagonal network with a 2D =4.01(a=11.347=2a 2D 2) (Fig. 5); three over seven nodes are occupied (Fig. 5). According to Grice et al. [13], this hexagonal network is characteristic of ‘flat-lying’ layers of carbonate groups (a2D ≈ 5.1 Å) found in numerous carbonates (CaCO3 calcite, Na5Y(CO3)4 [3]). The smaller a2D parameter observed in Na3Y(CO3)3 ˙6 H2O is due to the out of plane tilt of the CO32– ions.

Fig. 4

Layers of carbonate groups at z ≈ 0.175 and z ≈ 0.675 in Na3Y(CO3)3 ˙6 H2O.

Fig. 5

Lacunar hexagonal network of carbonate groups in Na3Y(CO3)3 ˙6 H2O.

A relationship between the structures of Na3Y(CO3)3 ˙6 H2O and of Na3(Y,REE)(CO3)3 ˙3 H2O shomiokite can be easily established: the c lattice parameters are similar because of the existence of [Na(CO3) ˙2 H2O] and [Na(CO3) ˙H2O] layers with a comparable thickness (Fig. 6 and Table 6). Moreover, Y3+ or Na+ coordinations are identical in both phases, as was previously indicated.

Fig. 6

[Na(CO3) ˙2 H2O] layers in Na3Y(CO3)3 ˙6 H2O.

Table 6

Structural relationship between Na3Y(CO3)3 ˙6 H2O, Na3(Y,REE)(CO3)3 ˙3 H2O shomiokite, and NaY(CO3)2 ˙6 H2O adamsite

Y and Na polyhedracell parametersspace group
Na3Y(CO3)3 ˙6 H2ONa[6] Y[9]11.3475.935P63
ShomiokiteNa[6] Y[9]10.04217.3495.948Pbn21
AdamsiteNa[6] Y[9]6.259213.083813.2271P1 ¯
91.130103.55490.188

5 Characterization

5.1 Thermal behaviour

On heating, Na3Y(CO3)3 ˙6 H2O exhibits a weight loss in three steps. The first step, which occurs around 125 °C, is attributed to the departure of six water molecules per mole Na3Y(CO3)3 ˙6 H2O (exp./th. = 24.7/24.2%). The anhydrous phase is amorphous and results from the reaction:

Na 3 Y( CO 3 ) 3 ·6H 2 O Na 3 Y( CO 3 ) 3 +6H 2 O

The second step corresponds to the departure of 1.5 mol of CO2 gas per mole of Na3Y(CO3)3 (exp./th. = 14.1/14.8%); the decomposition reaction is:

Na 3 Y( CO 3 ) 3 0.5Y 2 O 3 +1.5 Na 2 CO 3 +1.5 CO 2

The third step is due to the decomposition of Na2CO3 and occurs above 850 °C.

5.2 Vibration analysis

In Na3Y(CO3)3 ˙6 H2O, the Y atom is on the threefold axis (2 b) and all the other atoms lie in general positions (6 c). Using the standard correlation method [14] in C66 (P63), the normal modes of vibration can be classified according to the irreducible representations of C6 (Table 7):

Γ M =34A34B34E 1 34E 2

Table 7

Vibrational analysis of Na3Y(CO3)3 ˙6 H2O

Factor group C6External modesInternal modesActivity
CO3H2O
NATCO3RCO3TYTNaTH2ORH2Oν1ν2ν3ν4νδγIRRaman
A34–13313661122222zαxx + αyy ; αzz
B3403313661122222
E134–13313661122222(x, y)(αxx, αyz)
E23403313661122222(αxx – αyy, αxy)

The acoustic modes are: Γacous = A ⊕ E1. The A and E1 modes are Raman and IR actives, while E2 modes are only Raman actives. B modes are inactive.

Free CO22– anion has the D3h symmetry and exhibits four normal vibrations ν1(A1′ ), ν2(A2′ ′ ), ν3(E′) and ν4(E′). E′ modes are IR and Raman actives, while A1′ is only Raman active and A2′ ′ is only IR active. ν1 (1000–1100 cm–1) and ν3 (1400–1500 cm–1) represent the symmetric and asymmetric stretching vibrations, respectively. ν2 (650–800 cm–1) and ν4 (800–1000 cm–1) correspond to out of plane and in plane deformation vibrations, respectively. The crystal modes (and the macroscopic geometry of observation) can be related to the previous modes by the so-called site method. In Na3Y(CO3)3 ˙6 H2O, the carbon site symmetry is C1; the correlation analysis is schematised in Table 8.

Table 8

Correlation scheme for the internal vibration modes of CO3 groups in Na3Y(CO3)3 ˙6 H2O

Fig. 7 shows the Raman spectrum. One line at 1065 cm–1 and two lines at 715 and 680 cm–1 are attributed to the ν1 and to the ν4 modes, respectively. Theoretically, three lines are expected for the ν1 mode and six lines for the ν4 mode (Table 7). Though no polarisation analysis was possible, these lines can be unambiguously assigned to the A mode as a reason of the diagonal form of the polarisability tensor. The ν2 and ν3 modes around 820 cm–1 and 1500 cm–1 are very weak. For the ν2 mode, this feature can be explained by the fact that ν2 derives from (A2′ ′ ), Raman inactive in D3h symmetry.

Fig. 7

Raman spectrum of Na3Y(CO3)3 ˙6 H2O.

The observed bands at low frequencies are very large. They are attributed to external modes of Na+ and Y3+ translations and H2O or CO32– translations and librations.

The IR spectrum is given in Fig. 8. The band around 1065 cm–1 and the shoulder observed at 1045 cm–1 are assigned to the symmetric stretching modes ν1 of CO32–. The two bands located at 890 and 875 cm–1 are attributed to the out-of-plane deformation modes ν2. In the region 1200–1550 cm–1, two large bands, around 1375 and 1485 cm–1, correspond to the asymmetric ν3 stretching. For the out-of-plane ν4 deformation, four bands predicted in the region 800–650 cm–1 are observed at frequencies 680, 715, 755 cm–1 and 760 cm–1 (shoulder). Then, it is noted that the number of theoretical and observed bands is identical for ν2 and ν4.

Fig. 8

IR spectrum of Na3Y(CO3)3 ˙6 H2O.

H2O vibration modes, attributed to antisymmetric stretching, symmetric stretching, in plane β-OH deformation and out of plane γ-OH deformation, are expected in the intervals 3600–2000, 1700–1550, 1300–1200 and 800–700 cm–1, respectively. Experimentally, only five very large bands in the region 3600–2000 cm–1, together with one small band at 1635 cm–1, are observed.

6 Conclusion

The crystal structure of a new hydrated carbonate, Na3Y(CO3)3 ˙6 H2O, is determined and can be described from lacunar layers of carbonate groups. A structural relationship is found with Na3(Y,REE)(CO3)3 ˙3 H2O shomiokite and both hydrates are acentric. IR and Raman spectroscopy studies of Na3Y(CO3)3 ˙6 H2O confirm the structural determination. It is observed that O–H vibration lines are very large and also weak, in spite of the presence of six water molecules for three carbonate groups.

It must be noted that shomiokite-(Y) mineral was found in association with an alteration yttrium carbonate. This silky white carbonate was too fine grained and the material quantity was too small; consequently, the structure is still unknown (J.D. Grice, personal communication). It should be interesting to collect X-ray diffraction and/or spectroscopic data of this carbonate, which could be compared with Na3Y(CO3)3 ˙6 H2O.

Acknowledgements

The authors are very indebted to Pr. A. Bulou (LPEC, Univ. Le Mans) for his help in the analysis of vibrational spectra and to Dr P. Aschehoug (LCAES, ENSC Paris) for the SHG test.


Bibliographie

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[14] W.G. Fateley; F.R. Dollish; N.T. McDevitt; F.F. Bentley, Infrared and Raman Selection Rules for Molecular and Lattice vibration: The correlation Method, Wiley-Interscience, New York, 1972


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