Synthesis, crystal structure, characterization and electrochemical properties of a new cyclohexaphosphate: Li2Na2CoP6O18·12H2O

Accepted Manuscript Synthesis, crystal structure, characterization and electrochemical properties of a new cyclohexaphosphate: Li2Na2CoP6O18·12H2O Samira Sleymi, Massoud Kahlaoui, Samiha Dkhili, Salma Besbes-Hentati, Sonia Abid PII:

S0022-2860(16)30775-X

DOI:

10.1016/j.molstruc.2016.07.091

Reference:

MOLSTR 22794

To appear in:

Journal of Molecular Structure

Received Date: 18 April 2016 Revised Date:

18 June 2016

Accepted Date: 20 July 2016

Please cite this article as: S. Sleymi, M. Kahlaoui, S. Dkhili, S. Besbes-Hentati, S. Abid, Synthesis, crystal structure, characterization and electrochemical properties of a new cyclohexaphosphate: Li2Na2CoP6O18·12H2O, Journal of Molecular Structure (2016), doi: 10.1016/j.molstruc.2016.07.091. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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ACCEPTED MANUSCRIPT Synthesis, crystal structure, characterization and electrochemical properties of a new cyclohexaphosphate: Li2Na2CoP6O18•12H2O

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Samira Sleymia, Massoud Kahlaouib, Samiha Dkhilia, Salma Besbes-Hentatia, Sonia Abida* a

Laboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna, Bizerte, Tunisia b Laboratoire de physique des matériaux, Unité de service commun spectromètre de surfaces, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna, Bizerte, Tunisia.

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* Corresponding author.

Abstract

A new cyclohexaphosphate with the Li2Na2CoP6O18•12H2O (LNCP) composition was prepared via a simple process at room temperature. This compound was characterized using X-ray diffraction (XRD), Infrared and UV-visible spectroscopy, Thermal analysis (TG),

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Cyclic voltammetry and Impedance spectroscopy. The results show that the LNCP was phased with a monoclinic structure and C2/c space group. The crystal structure was solved by

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using 3893 independent reflections with a final R value of 0.055. The P6O18 ring is centrosymmetrical. Its main geometrical features are those commonly observed in the atomic

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arrangements of cyclohexaphosphate. The atomic arrangement of this compound can be described by an organization in a three-dimensional framework, formed by the anions (P6O18)6- and polyhedra of lithium and sodium. This structure has channels where octahedral cobalt is housed. By means of a cyclic voltammetry study, it is shown that this substrate undergoes a multistep anodic oxidation, leading to a thin and compact electroactive deposit. The electrical conductivity was studied using two-probe impedance spectroscopy and results showed that the conductivity of LNCP at 518 K was equal to 1.74×10-4 Scm-1. Keywords: Polyphosphate, Crystal structure, Li-ion battery, Electrical properties.

ACCEPTED MANUSCRIPT 1. Introduction The synthesis and characterization of new transition metal phosphates continues to be an attractive field of research for solid state chemists because these materials have interesting applications in different areas such as catalysis, ionic conductivity, industrial coatings,

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biosensor manufacture and electrochemistry. [1-3]. In the structures formed, metals can adopt various coordination polyhedra (octahedron, trigonal bipyramid, tetrahedron, squared pyramid, etc.) which often display with the phosphate groups variable connecting modes

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giving rise to versatile frameworks [4]. Research on the synthesis of lithium transition-metal phosphates further intensified with the discovery of the electrochemical properties of the

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olivine-type phases LiMPO4 (M = Mn [5], Fe [6], Co [7], Ni [8]). As an important class of phosphate, cyclohexaphosphates have received considerable interest in the past few decades due to their high hydrolytic and thermal stabilities, and pronounced complexation ability [9]. It is noteworthy that the metal cyclophosphate compounds show a hierarchy of structures with

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different dimensionalities. These include one-dimensional (1D) chains [10], two-dimensional (2D) layers [11] and a complex three-dimensional (3D) structure [12, 13]. Although the study of metal phosphates is conspicuous and some inspiring results have been recently achieved,

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there is very scant information on the ternary alkali metal cyclohexaphosphates in the literature. So far only one case of a mixture of two alkalines and a cyclohexaphosphate with

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bivalent cations has been reported [13]. In industrial phosphoric acid, the high resistance of stainless steel to corrosion has been considered as the consequence of the formation of a porous polyphosphate film [14]. In this work, we report the synthesis of a novel dilithium disodium

cobalt

cyclohexaphosphate

dodecahydrate,

Li2Na2CoP6O18•12H2O.

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physicochemical properties were studied using X-ray diffraction and FTIR spectra. Then, the electrochemical oxidation of this cyclohexaphosphate was conducted by means of a

ACCEPTED MANUSCRIPT potentiodynamic technique to obtain the corresponding electrodeposit. The electrical properties of the abovementioned material and its comparison to other results were studied. 2. Experimental section 2.1. Synthesis

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0.808 g (10-3mol) of Li6P6O18•6H2O, which has been prepared according to the Schülke and Kayser procedure [15], was mixed in 50 mL of distillated water to 0.237 g (10-3mol) of CoCl2•6H2O and 0.170 g (2×10-3mol) of NaNO3 under mechanical stirring for 30 min, at

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room temperature. After this step, the obtained solution was allowed to stand in air until the

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formation of good quality pinkish single crystals. A yield of 67 % was calculated for Li2Na2CoP6O18•12H2O. 2.2. Analytical Methods

UV-vis diffuse reflectance was performed on a Perkin Elmer Lambda-45 spectrophotometer

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coupled with an integration sphere type RSA-PE-20 in the 400–800 nm range with a speed of 960 nm. min-1 and an aperture of 4 nm. The electronic absorption spectrum was obtained for an aqueous solution of the complex (c = 1.24×10-4 M) with a Perkin-Elmer Lambda-11 UV-

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vis spectrometer in the 400–800 nm range, using a 10 mm quartz cell. Infrared (IR) spectra were recorded at room temperature on a Nicolet IR 200 FTIR spectrophotometer in the 4000–

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400 cm-1 region.

Powder X-ray diffractions (PXRD) were collected with a BRUKER D8 ADVANCE X-ray diffractometer using graphite monochromatized CuKα radiation (λ= 0.154 nm) for 2h in the 2θ range from 9 to 40°.

X-ray data was collected on an Enraf Nonius Mach3 diffractometer, using graphite monochromated AgKα radiation (λ = 0.5608 Å). The structure was solved by direct methods and refined with full-matrix least-squares on F2 using SHELXS-97 and SHELXL-97 [16, 17]. All non-hydrogen atoms were refined anisotropically. The hydrogen atoms were located in a

ACCEPTED MANUSCRIPT difference Fourier map but constrained to ride on their parent atoms with Uiso(H) = 1.5Ueq(O). The crystallographic data is reported in Table 1, the selected bond lengths and angles for the phosphoric ring and for all the cation polyhedra are listed in Table S1 and Table 2, respectively.

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The TG-DTA experiments were carried out with 18.00 mg of LNCP. The sample was placed on an open platinum crucible and heated, under Argon at a heating rate of 5 K min-1, from room temperature to 823 K; an empty crucible was used as reference.

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The voltammetric study was performed using a Tacussel potentiostat (PGP 201) in a threeelectrode cell with compartments separated by a porous glass. The working electrode was a

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gold disk (Ø= 2 mm, EDI type Radiometer) and the counter electrode was a platinum wire. AgCl/ Ag was used as the reference electrode. All experiments were carried out at room temperature (25 ± 2 °C).

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Electrochemical impedance spectra (EIS) were obtained using a Hewlett-Packard HP 4192 analyzer. The impedance measurements were taken in an open circuit using two electrode configurations with a signal amplitude of 50 mV and a frequency band ranging from 5 Hz to

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13MHz. Both pellet surfaces were coated with silver paste electrodes while the platinum wires attached to the electrodes were used as current collectors. All these measurements were

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performed at equilibrium potential at a temperature ranging between 313 K and 518 K. In order to obtain the ionic conductivity, the resulting data was analyzed using the equivalent circuit of the Z-View software. 3. Results and discussion 3.1. Crystal structure The PXRD pattern of the synthesized product is in good agreement with the calculated pattern from the single crystal data, indicating its phase purity (Fig. 1a). The difference in intensity of some diffraction peaks may be attributed to the preferred orientation of the crystalline powder

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single-crystal

structure

determination

performed

here

confirms

that

Li2Na2CoP6O18•12H2O is isostructural to the previously reported Li2Na2NiP6O18•12H2O [13].

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Thus, the title compound is the second cyclohexaphosphate with a mixture of two alkalines and bivalent cations to be reported. It crystallizes in a centrosymmetric C2/c space group, with one Co atom in a special position, one Lithium atom, one sodium atom, half a

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phosphoric ring P6O18, and 6 crystallographically distinct water molecules in an asymmetric unit (Fig. 1c). The phosphoric ring located around the (¼, ¼, 0) inversion center ring adopts a

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centrosymmetric chair conformation where the P(1), P(2), P(1)ii and P(2)ii atoms constitute a plane, and where P(3) and P(3)ii are outside this plane (Fig. 2a). Interatomic bond distances and angles within the phosphoric ring (P-O and O-O distances, O-P-O and P-O-P angles) are in agreement with previous structural information about cyclohexaphosphates anions [19, 20].

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The P6O18 units and the NaO6 octahedra are linked by sharing vertices, giving rise to anionic inorganic layers parallel to the ab-plane, containing six membered rings (Fig. 2b). Among the six oxygen atoms of the sodium octahedra, three form Na-O-P linkages with three

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independent phosphorus atoms (average Na-O-P = 124.18 °) and the remaining oxygen as terminal Na-OH2 bonds. The LiO4 tetrahedra share vertices with the phosphate tetrahedra

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from adjacent layers, thereby connecting the layers and forming a three-dimensional framework (Fig. 2c). This connectivity gives rise to channels running along the b axis (Fig. 2d) in which the six-coordinated Co2+ cations are located. The CoII cation exhibits a slightly distorted octahedral arrangement of water molecules with Co–O distances ranging from 2.075 (3) to 2.111 (3) Å. The smallest distance between two octahedral centers is 8.95 Å. Topologically, if the Co(H2O)6 may be considered as a node, it acts as a four-connecting node

ACCEPTED MANUSCRIPT to link 6 crystallographic equivalent ones, forming a 3D cage network. A phosphate ring is lodged at the center of each cage (Fig. 2e). 3.2. Thermal Analysis The thermal stability of the elaborated complex is studied by thermogravimetric and

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differential thermal (TG-DTA) analyses, carried out in Argon atmosphere from ambient temperature to 823 K. The TG and DTA curves are shown in (Fig. 3a). The DTA curve shows 2 endothermic peaks at 398 and 415 K related to the loss of all hydration water molecules, the

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corresponding weight loss (25.555%) is in good accordance with the calculated value (26.709%). From the XRD, it was established that dehydration is accompanied by a phase

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transformation. Fig. 3b shows the changes in the diffraction patterns for sample Li2Na2CoP6O18•12H2O measured as synthesized and after heat treatment at 500 K for 1h. The infrared absorption spectrum of the heat treated sample is characterized by the complete disappearance of the bands of the stretching and bending modes of water molecules and by

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the presence of the characteristic absorption bands of linear phosphates at ~910 cm-1 (asymmetric stretching modes of the in-chain P – O – P linkages) (Fig. 4a) [21]. 3.3. Infrared Spectroscopy and Electronic Spectra

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The infrared spectrum (Fig. 4b) shows broad bands in the 3600-2800 and 1600-1800 cm-1 ranges corresponding, respectively, to the stretching and bending vibrations of water

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molecules.

The broadness of the corresponding bands is indicative of the formation of hydrogen bonds of varying strengths in the structure. In comparison with the IR spectra of other cyclohexaphosphates [22], it is evident that the bands in the 1350-1180 cm-1 region are due to the OPO symmetric and anti-symmetric vibrations within the phosphate rings while those that appear between 850 and 660 cm-1 can be assigned to νas (POP)- and νs (POP)- modes of the POP bridge, respectively. Frequencies below 660 cm-1 correspond to the bending vibration of

ACCEPTED MANUSCRIPT P6O18 ring, whereas Co-O vibrations could not be observed as they are expected to lie below 500 cm-1. The diffuse reflectance spectrum of the presented complex (Fig. S1a), presents a broad

4

T1g(F) →

4

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band at 516 nm and a shoulder at 470 nm, assigned to d-d transitions, 4T1g(F) → 4A2g(F) and T1g(P), respectively. These transitions are in conformity with octahedral

arrangements for the Co(II) ion [23]. The electronic absorption spectrum of the title compound in aqueous solution (Fig. S1b) differs little from the diffuse reflectance spectrum

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of the solid, suggesting that the complex maintains its octahedral geometry in solution. The

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third peak corresponding to the spin allowed transition 4T1g→ 4T2g(F) was expected in the NIR region (around 1111 nm) but could not be observed because of the limited range of the instrument used. 3.4. Cyclic Voltammetry

Fig. 5a shows several repetitive cyclic voltammetry curves of Li2Na2CoP6O18•12H2O (10-3

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M) in aqueous solution with NaCl 1M as electrolyte. All the potential values are quoted versus the AgCl/ Ag electrode reference. During the anodic scanning, the first and second cycles show a poorly defined oxidation process at about 1.5 V, which corresponds to cobalt

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oxidation according to reaction: Co2+
Co3++ 1e- (E° vs AgCl/ Ag/ V = 1.62).

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In the reverse direction, a very large cathodic wave is observed in its potential range. From the third to the tenth cycle the characteristics of the anodic peak remain approximately constant and reproducible results are obtained. However, from the twenty-fifth cycle, the voltammogram of Li2Na2CoP6O18•12H2O exhibits a supplementary rather thin anodic peak at about 0.43 V. Its magnitude is fairly similar to that of the initial one, which shifts to more a cathodic potential and becomes more defined than before (1.04 V). From the cathodic direction, two reduction and overlapped reduction steps are observed at about 0.64 and 0.32 V. Progressively, the electrode surface is modified by the appearance of a pinkish film that

ACCEPTED MANUSCRIPT covers it. Based on the redox potential of each ion, the redox currents can be assigned to Co3+/Co2+. Despite all these observations, it is still unclear which additional coupling steps take place on the electrode during the nucleation of the inorganic layer. Around the 40th cycle, the coated electrode was rinsed with water to remove the solution of

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the transition metal phosphate and was characterised by FTIR spectroscopy and cyclic voltammetry in an aqueous solution of 1 mol L-1 NaCl without the initial substrate.

The electroactivity of the modified surface showed an important variation with the potential

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cycling (Fig. 5b). From the 1st to the 10th cycles the obtained voltammograms didn’t show any electrochemical processes during the anodic scanning, while multistep oxidation waves and

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crossing were observed from the cathodic direction. Their voltammetric characteristics differ noticeably in shape and position. Therefore, the first potential scan, at the freshly immerged coated electrode exhibits two cross over phenomena (CO1 and CO2), at about 1.09 and 0.78 V. Besides, three large anodic waves were noticed at potentials of 0.96, 0.76 and 0.58 V. For the

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second scan, two crossings and four oxidation steps were observed at notably different potential values than those of cycle 1 (Table. 3). From the fourth cycle on, the accessible anodic potentials became higher with the appearance of only one CO phenomenon at 0.76 V,

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in which more than five closely-spaced waves appeared. Such features are characteristic of the formation of a new phase [24-27], in which the nucleation overpotential is required. A

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gradual increase in current with each cycle of the multisweep cyclic voltammogram was also observed (Fig. 5b).

From the 13th cycle onwards, the crosses disappeared completely,

revealing a large and very important anodic wave, showing a cathodic process of the same magnitude in its potential field. The shape and position of these waves remained unchanged during the subsequent cycles. FTIR characterization of the film formed showed a quite dissimilar spectrum (Fig. S2). The broad bands of the water molecules remained observable in the 3600 to 2800 and 1800 to

ACCEPTED MANUSCRIPT 1600 cm-1 range. The OPO symmetric and anti-symmetric vibrations within the PO4 tetrahedra, those of the νas (POP)- and νs (POP)- modes of a POP bridge as well as those of the corresponding bending vibration, appeared as overlapped bands from 1250 to 750 and from 750 to 500 cm-1, respectively. When comparing the spectrum of the coated film to that

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of the heated Li2Na2CoP6O18•12H2O at 500 K, similarities could be observed in the region of the phosphate bands. Especially for the bands at 910 cm-1 that might correspond to linear phosphates [21]. Thus, these spectroscopic characteristics indicate the formation of a new

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compound which probably corresponds to a hydrated polyphosphate.

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3.5. Electrical properties

Electrical conductivity of the samples was studied using the widely used technique of AC impedance spectroscopy (IS). Fig. 6 shows the Nyquist diagram obtained on pellets of Li2Na2CoP6O18•12H2O at different temperatures. It can be seen that the impedance spectrum is composed of complete semi-circles; a partial arc is clearly seen from 443 K. It is worth to

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note that the material shows a good response from the dehydrated state. According to the thermal analysis, the mechanisms of conductivity are obvious after the transformation of the product into an anhydrous polyphosphate (1), excluding a protonic conductivity contribution

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[28]. The presence of single semicircular arcs indicates that the electrical processes in the

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material arise basically due to the contribution from the bulk material [29]. The various electrochemical contributions of material overlap require the refinement of the mathematical model by taking, once again, various parameters such as the resistance (R) and the constant phase element (CPE). In order to characterize the experimental Nyquist diagrams, a model series as that shown in Fig. 6 was used for simplicity reasons. The contributions resulted in a series of R-CPE couples. In the equivalent circuit model, Rs is the ohmic resistance of the samples and R is the overall resistance. The quality of the contributions depends on the temperature. The conductivity can be obtained using the following equation:

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= ×

Where e is the thickness of the sample and S is the electrode surface area of. The ratio e/S is the sample’s geometric factor. The Arrhenius plot of log conductivity against reciprocal temperature is shown in Fig. S3.

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The activation energy (Ea) was calculated by fitting the conductivity data to the Arrhenius relation for thermally activated conduction, given by: 

)



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σT = σ exp (−

Where σ, T, k, Ea and σ0 are: the conductivity, absolute temperature, Boltzmann constant,

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activation energy and a pre-exponential factor, respectively.

The calculated conductivity and activation energy of this composition were equal to 1.74×10-4 Scm-1 at 518 K and 1.23 eV, respectively. Comparing to other phosphate products (Table 4), the ionic conductivity of the anhydrous polyphosphate of LNCP is better than that of

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NaCo(PO3)3 and LiMg3(PO4)P2O7. Nevertheless, this conductivity is lower than that of NASICON-type phosphate and Li-containing garnets. 4. Conclusion

metal

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In this paper we have reported the synthesis and the characterization of a novel transition cyclohexaphosphate.

To

our

knowledge,

this

compound

is

the

second

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cyclohexaphosphate with a mixture of two alkalines and bivalent cations ever to be reported. This research shows that the P6O18, as a typical polydentate oxygen donor, can be assembled with metal polyhedra to produce an interesting structure and with a high dimensional architecture. Its corresponding coating electrode could be regarded as promoting the polyphosphate thin film, which would serve as anticorrosive protection and in batteries. Electrical properties of Li2Na2CoP6O18•12H2O have been studied in a large temperature range, from 413 K to 518 K. The highest conductivity value is 1.74 Scm-1 at 473 K with an activation energy equal to 1.23 eV.

ACCEPTED MANUSCRIPT Acknowledgements This work was supported by the Ministry of Higher Education and Scientific Research of Tunisia. The author would also like to thank Prof. M. Rzaigui for the X-ray analysis and the language expert Nayua Abdelkefi for proofreading the manuscript.

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M. Casciola, U. Costantino, L. Merlini, I.G. Krogh Andersen, E. Krogh Andersen, Preparation, Structural Characterization and Conductivity of LiZr2(PO4)3, Solid State Ionics 26 (1988) 229–235.

[34]

V. Thangadurai, H. Kaack, W. J. F. Weppner, Novel Fast Lithium Ion Conduction in

R. Murugan, V. Thangadurai, W. Weppner, Fast Lithium Ion Conduction in Garnet-

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Type Li7La3Zr2O12, Angew. Chem. Int. Ed. 46 (2007) 7778–7781.

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[35]

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Garnet-Type Li5La3M2O12 (M = Nb, Ta), J. Am. Ceram. Soc. 86 (2003) 437–440.

ACCEPTED MANUSCRIPT Figure Captions

Fig. 1 : (a) Simulated and experimental X-ray powder diffraction patterns of Li2Na2CoP6O18.12H2O. (b) Morphology of Li2Na2CoP6O18.12H2O crystal with (hkl) faces. (c) An ORTEP view of Li2Na2CoP6O18.12H2O with the atom-labeling. Displacement ellipsoids are drawn at 50% probability. H-atoms are represented as small arbitrary radii.

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Fig. 2 : (a) Schematic representation of the chair conformation of the P6O186- ring. (b) A Projection, along the c direction, of an isolated anionic layer. (c) A projection along the b axis of the atomic arrangement of Li2Na2CoP6O18.12H2O. (d) A perspective view showing the channel running along the b-axis. (e) The 3D four-connected cobalt nodes forming cages containing the phosphoric anions.

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Fig. 3 : (a) DTA and TGA curves of Li2Na2CoP6O18.12H2O at rising temperature. (b) X-ray powder diffraction patterns of Li2Na2CoP6O18.12H2O at ambient and at 500 K.

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Fig. 4 : IR spectra of Li2Na2CoP6O18.12H2O : at 500 K (a), at ambient (b).

Fig. 5 : Repetitive cyclic voltammograms in aqueous solution of NaCl + 0.1 mol dm-3, at 0.1 Vs-1 of : (a) Li2Na2CoP6O18.12H2O at 1.0 mM, (b) coated electrode.

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Fig. 6 : Impedance spectra and equivalent circuit model at different temperature in air.

ACCEPTED MANUSCRIPT Table 1 : Crystal data and structure refinement parameters of CoLi2Na2P6O18.12H2O CoH24Li2Na2O30P6

Formula weight (g mol-1)

808.80

Crystal system

Monoclinic

Space group

C2/c

a (Å)

17.789 (11)

b (Å)

10.243 (5)

c (Å)

14.810 (11)

β (°)

112.175 (5)

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V (Å 3) Z Calculated density (g cm-3) Absorption coefficient (mm-1) Crystal size (mm)

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F(000)

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2499 (3)

Limiting indices

4 2.150 0.64

0.40 × 0.35 × 0.30 1636

-17 ≤ h ≤ 17, -5 ≤ k ≤ 12, -18 ≤ l ≤ 3 2186/23/222

Goodness-of-fit on F2

1.04

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Data/restraints/parameters

R1 = 0.0547, wR2 = 0.1175

R indices (all data)

R1 = 0.0724, wR2 = 0.1280

∆ρmax, ∆ρmin /e Å-3

0.67 ; −0.70

CCDC

1456462

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Final R indices [I > 2σ(I)]

ACCEPTED MANUSCRIPT Selected bond lengths (Å) and angles (°) in Co(H2O)6 octahedron O(W4)

O(W5)

O(W6)

O(W4)

2.111 (3)

3.020(9)

2.980(5)

O(W5)

91.74 (12)

2.095 (3)

4.169(5)

O(W6)

90.75 (13)

177.09 (12)

2.075 (3)

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Co(1)

Selected bond lengths (Å) and angles (°) in NaO6 octahedron O(W1)

O(W2)

O(W3)

O(E12)vii

O(W1)

2.565 (4)

3.098(6)

3.150(5)

4.948(6)

O(W2)

78.26 (15)

2.337 (5)

3.128(7)

O(W3)

O(E31)vi

3.813(13)

3.446(6)

3.676(7)

3.417(9)

4.681(8)

75.82 (13)

79.21 (16)

2.561 (4)

3.550(12)

4.932(16)

3.667(8)

vii

166.64 (14)

101.28 (16)

90.93 (13)

2.418 (4)

3.472(5)

3.429(5)

i

100.73 (13)

92.71 (16)

vi

88.35 (13)

166.48 (16)

O(E21) O(E31)

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171.68 (14)

92.64 (13)

2.384 (4)

3.412(5)

95.84 (13)

91.30 (13)

91.60 (14)

2.377 (4)

Selected bond lengths (Å) and angles (°) in LiO4 tetrahedron O(E32)vi

O(W1)

O(W3)ix

O(E11)iv

1.926 (9)

3.270(6)

3.133(11)

3.272(5)

vi

115.8 (4)

1.935 (9)

3.209(8)

3.144(6)

O(W1)

107.2 (4)

110.6 (4)

1.967 (9)

3.049(5)

O(W3)ix

114.0 (4)

107.1 (4)

101.3 (4)

1.975 (9)

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O(E11)iv

Li(1)

−x+1/2, y+1/2, −z+3/2.

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Symmetry codes: (i) −x, y, −z+1/2; (iv) −x+1/2, −y+1/2, −z+1; (vi) x, −y+1, z+1/2; (vii) x, −y, z+1/2; (ix)

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CO2

Step 1

Step 2

Step 3

Step 4

1

1.09

0.78

0.96

0.76

0.58

2

1.44

0.76

1.24

1.10

0.98

3

1.48

0.8

1.30

1.16

0.83

4

0.74

1.50

1.42

1.28

1.1

5

0.72

1.4

1.32

1.24

1.2

6

0.66

1.32

1.28

1.22

1.08

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Step 7

Step 8

0.76

0.82

1.08

0.98

0.9

0.92

0.67

0.59

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Number of Cycle

0.74

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σ (Scm-1)

References

LiNiPO4

2.34 10-7

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NaCo(PO3)3

1.01 10

-5

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LiMg3(PO4)P2O7

3.40 10-5

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Anhydrous LNCP

1.74 10-4

This work

LiZr2(PO4)3

2 10-3

Li5La3Ta2O12

2.5 10-2

Li7La3Zr2O12

4.0 10-2

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Compounds

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The atomic arrangement shows three-dimensional network.

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FT-IR and UV–vis spectra were measured.

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New mixed cobalt(II) lithium sodium cyclohexaphosphta Li2Na2CoP6O18.12H2O, was synthesized.

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This material was also investigated by Cyclic voltammetry and Impedance spectroscopy.