Ionic conductivity and structural characterization of Na 1.5Nb 0.3Zr 1.5(PO 4) 3 with NASICON-type structure (original) (raw)
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Crystal chemistry and ion conductivity of the Na1 + xTi2 − xAlx(PO4)3 (0 ≤ x ≤ 0.9) NASICON series
Journal of Materials Chemistry, 2000
The Na 1zx Ti 22x Al x (PO 4 ) 3 (0.0¡x¡0.9) solid solution has been prepared as a polycrystalline powder. These compounds crystallise in the NASICON type structure, R3 Å c space group, and the crystal structures have been characterised by the Rietveld method with laboratory powder diffraction data. The Ti/Al atoms are randomly distributed over the octahedral site of the NASICON framework. The negatively charged framework is neutralised by the Na z cations which are distributed over the M1 site, fully occupied, and M2 site, partly occupied. The cell parameter evolution along the series agrees with the substitution of larger Ti 4z by smaller Al 3z cations. The thermal expansion coef®cients were determined from a thermodiffractometric study of Na 1.8 Ti 1.2 Al 0.8 (PO 4 ) 3 . The ion conductivity of the samples rises as the charge carrier number (x) increases. The activation energies deduced from the Arrhenius plots are close to 0.50 eV. The overall conductivities are near to 10 25 S cm 21 at 200 ³C.
Ceramics International, 2009
Na 3 MgZr(PO 4) 3 and Na 0.1 (H 3 O) 2.9 MgZr(PO 4) 3 were prepared by microwave heating and ion exchange methods respectively. They were characterized by powder XRD, energy dispersive spectroscope (EDS), IR, Raman, TGA/DTA, DC conductivity and 31 P-MAS NMR spectra. These two compounds crystallized in the hexagonal NASICON lattice with R3 c space group. The EDS spectra show the replacement of Na + by H 3 O + ions. The infrared and Raman spectra exhibit characteristic vibrational bands of PO 4 tetrahedra and metal-oxygen vibrations. The DTA and TGA studies respectively indicate the structural phase transformations and absence of weight loss in these phosphates. The activation energies for conduction was found to be higher Na 3 MgZr(PO 4) 3 compare to the value obtained for Na 0.1 (H 3 O) 2.9 MgZr(PO 4) 3 and the values obtained are 0.41 and 0.082 eV (in the temperature range 27-165 and 165-360 8C) respectively. The DC conductivity of Na 3 MgZr(PO 4) 3 is higher than the conductivity of Na 0.1 (H 3 O) 2.9 MgZr(PO 4) 3. The conductivity values are found to be as s dc = 1 Â 10 À4 V À1 cm À1 and s dc = 1 Â 10 À6 V À1 cm À1 at 250 8C respectively. The 31 P-MAS NMR spectra show the presence of two chemically different environments around phosphorous in these compounds.
Designing High Ionic Conducting NASICON-type Na3Zr2Si2PO12 Solid-Electrolytes for Na-Ion Batteries
The Journal of Physical Chemistry C, 2020
The present work investigates the synthesis and characteristics of Na Super-Ionic Conductor (NASICON)-type Sc 3+-and Yb 3+-doped Na3Zr2Si2PO12 solid electrolyte for application in solid-state Na-ion batteries. A significant improvement of Na-ion conductivity in Na3Zr2Si2PO12 has been achieved through crystal engineering and microstructure refinement. The presence of monoclinic-ZrO2 impurity phase adversely affecting the Na-ion conductivity is eliminated by using cubic-ZrO2 precursor at the place of monoclinic-ZrO2 in conventional solid-state reaction method. Utilizing cubic-ZrO2 also refined the microstructure with thin and microcracks free grain boundaries. A replacement of 16.5 at.% of Zr 4+ by Sc 3+ in Na3Zr2Si2PO12 enhances the room-temperature total ionic conductivity from 0.61 mS.cm-1 to 0.96 mS.cm-1. Replacing 11.11 at.% of Sc 3+ by Yb 3+ further improves the room-temperature ionic conductivity to 1.62 mS.cm-1 which is >2.5 times higher than that of bare Na3Zr2Si2PO12. The strategic approach used to raise the ionic conductivity in the current work can be applied to other materials, paving a way towards realizing high-performance solidelectrolytes for viable and economic Na-ion batteries. A room-temperature conductivity of 1.51 mS.cm-1 for Sc 3+ /Yb 3+-doped Na3Zr2Si2PO12 measured employing Na-metal as electrodes confirms Na-ion conduction. Furthermore, a very low current density (~10-7 A/cm 2) in the cyclic-voltammetry profile of Na│solid-electrolyte│Na cell demonstrates the suitability of Sc 3+ /Yb 3+-doped Na3Zr2Si2PO12 as a solid-electrolyte for Na-ion batteries. A detailed analysis of these materials has been performed, and the possible reasons for the conductivity enhancement are discussed.
Powder Diffraction, 1997
It is known that solids with composition Na3Zr 2 Si2PO 12 heated at 1200 °C crystallize in the nasicon structure. This material shows a high ionic conductivity that represents an interesting improvement in the field of solid electrolytes. Our experimental results allow to establish for the first time that nasicon structures are stable along the compositional join Na 3 Zr 2-^/4Si2x Pi + x ®\2 w i m x extending from 0 to 1.667. These structures are characterized by a Zr underoccupation of octahedral sites and a constant number of Na + ions. This fact envisages a possible application of these materials in the field of ceramic sensors and ionic conductors.
Journal of Materials Science, 2019
In this work, the effect of varying the size of the precursor raw materials SiO2 and ZrO2 in the solid-state synthesis of NASICON in the form Na3Zr2Si2PO12 was studied. Nanoscale and macro-scale precursor materials were selected for comparison purposes, and a range of sintering times were examined (10, 24 and 40 h) at a temperature of 1230 °C. Na3Zr2Si2PO12 pellets produced from nanopowder precursors were found to produce substantially higher ionic conductivities, with improved morphology and higher density than those produced from larger micron-scaled precursors. The nanoparticle precursors were shown to give a maximum ionic conductivity of 1.16 × 10−3 S cm−1 when sintered at 1230 °C for 40 h, in the higher range of published solid-state Na3Zr2Si2PO12 conductivities. The macro-precursors gave lower ionic conductivity of 0.62 × 10−3 S cm−1 under the same processing conditions. Most current authors do not quote or consider the precursor particle size for solid-state synthesis of Na3Z...
Materials Research Bulletin, 2003
The compound Tl 3 Nb 5 O 11 (PO 4 ) 2 has been prepared both in crystalline and powdery forms by the usual ceramic method. Isotypic powdered A 3 Nb 5 O 11 (PO 4 ) 2 (A ¼ Na, K) compounds have been synthesized by ''soft chemistry'' using ion exchange. Tl 3 Nb 5 O 11 (PO 4 ) 2 is rhombohedral (R 3c) with a H ¼ 13:014ð2Þ, c H ¼ 53:614ð9Þ Å , Z ¼ 18. Its crystal structure has been determined using single crystal X-ray data. Structure refinements carried out by the full matrix least squares method led to agreement factors R 1 ¼ 0:0451, WR 2 ðF 2 Þ ¼ 0:0987 and Goof ¼ 2:003. The anionic framework [Nb 5 O 11 (PO 4 ) 2 3À ] built up of corner-shared NbO 6 octahedra and PO 4 tetrahedra and delimiting interconnected tunnels is derived from the pure octahedral pyrochlore structure. Unlike Rb þ in the isostructural compound Rb 3 Nb 5 O 11 (PO 4 ) 2 , each of the monovalent Tl þ cations is split up into several site positions close to one another. Ionic conductivity measurements on the A 3 Nb 5 O 11 (PO 4 ) 2 (A ¼ Tl, K, Na) compounds, using the complex impedance method, indicate that the sodium compound presents better ionic properties than the potassium and thallium compounds, as shown by a lower activation energy and a higher conductivity. #
The crystal structures of the ion conductors (NH+4)Zr2(PO4)3and (H3O+)Zr2(PO4)3
Solid State Ionics, 1985
The crystal structures of (NH$) Zr2 (PO& and (H30+) Zr2 (PO& have been determined from neutron time-offlight powder diffraction data obtained at 15 K. Both compounds are rhombohedral, R%, with cell parametersa = 8.7088(l) and c = 24.2197(4) A for the ammonium compound anda = 8.7528(2), c = 23.6833(11) A for the hydroniurn compound. In both cases the ions are completely localized in the type I cavities and hydrogen bonded to lattice oxygens. The measured unit cell parameters are relatively large for this class of compounds but the entrance ways into the cavities are still too small to allow for unrestricted movement of the ions. Thus the low conductivity of the hydronium ion is related to this and other structural features.
Local structure and ionic conductivity in the Zr2Y2O7Y3NbO7 system
Journal of Physics: …, 2009
The Zr 0.5−0.5x Y 0.5+0.25x Nb 0.25x O 1.75 solid solution possesses an anion-deficient fluorite structure across the entire 0 x 1 range. The relationship between the disorder within the crystalline lattice and the preferred anion diffusion mechanism has been studied as a function of x, using impedance spectroscopy measurements of the ionic conductivity (σ ), powder neutron diffraction studies, including analysis of the 'total' scattering to probe the nature of the short-range correlations between ions using reverse Monte Carlo (RMC) modelling, and molecular dynamics (MD) simulations using potentials derived with a strong ab initio basis. The highest total ionic conductivity (σ = 2.66 × 10 −2 −1 cm −1 at 1473 K) is measured for the Zr 2 Y 2 O 7 (x = 0) end member, with a decrease in σ with increasing x, whilst the neutron diffraction studies show an increase in lattice disorder with x. This apparent contradiction can be understood by considering the local structural distortions around the various cation species, as determined from the RMC modelling and MD simulations. The addition of Nb 5+ and its stronger Coulomb interaction generates a more disordered local structure and enhances the mobility of some anions. However, the influence of these pentavalent cations is outweighed by the effect of the additional Y 3+ cations introduced as x increases, which effectively trap many anions and reduce the overall concentration of the mobile O 2− species.