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Title: Effect of sintering on the ionic conductivity of garnet-related structure Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} and In- and K-doped Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}

Abstract

Garnet-structure related metal oxides with the nominal chemical composition of Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}, In-substituted Li{sub 5.5}La{sub 3}Nb{sub 1.75}In{sub 0.25}O{sub 12} and K-substituted Li{sub 5.5}La{sub 2.75}K{sub 0.25}Nb{sub 2}O{sub 12} were prepared by solid-state reactions at 900, 950, and 1000 deg. C using appropriate amounts of corresponding metal oxides, nitrates and carbonates. The powder XRD data reveal that the In- and K-doped compounds are isostructural with the parent compound Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}. The variation in the cubic lattice parameter was found to change with the size of the dopant ions, for example, substitution of larger In{sup 3+}(r {sub CN6}: 0.79 A) for smaller Nb{sup 5+} (r {sub CN6}: 0.64 A) shows an increase in the lattice parameter from 12.8005(9) to 12.826(1) A at 1000 deg. C. Samples prepared at higher temperatures (950, 1000 deg. C) show mainly bulk lithium ion conductivity in contrast to those synthesized at lower temperatures (900 deg. C). The activation energies for the ionic conductivities are comparable for all samples. Partial substitution of K{sup +} for La{sup 3+} and In{sup 3+} for Nb{sup 5+} in Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} exhibits slightly higher ionic conductivity than that of the parent compound over the investigatedmore » temperature regime 25-300 deg. C. Among the compounds investigated, the In-substituted Li{sub 5.5}La{sub 3}Nb{sub 1.75}In{sub 0.25}O{sub 12} exhibits the highest bulk lithium ion conductivity of 1.8x10{sup -4} S/cm at 50 deg. C with an activation energy of 0.51 eV. The diffusivity ('component diffusion coefficient') obtained from the AC conductivity and powder XRD data falls in the range 10{sup -1}-10{sup -7} cm{sup 2}/s over the temperature regime 50-200 deg. C, which is extraordinarily high and comparable with liquids. Substitution of Al, Co, and Ni for Nb in Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} was found to be unsuccessful under the investigated conditions.« less

Authors:
 [1];  [2]
  1. Chair for Sensors and Solid State Ionics, Faculty of Engineering, University of Kiel, Kaiserstr. 2, D 24143-Kiel (Germany). E-mail: vt@tf.uni-kiel.de
  2. Chair for Sensors and Solid State Ionics, Faculty of Engineering, University of Kiel, Kaiserstr. 2, D 24143-Kiel (Germany)
Publication Date:
OSTI Identifier:
20784946
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 179; Journal Issue: 4; Other Information: DOI: 10.1016/j.jssc.2005.12.025; PII: S0022-4596(05)00613-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACTIVATION ENERGY; CHEMICAL COMPOSITION; CUBIC LATTICES; DOPED MATERIALS; GRAIN BOUNDARIES; INDIUM IONS; IONIC CONDUCTIVITY; LANTHANUM COMPOUNDS; LANTHANUM IONS; LATTICE PARAMETERS; LITHIUM COMPOUNDS; LITHIUM IONS; NIOBIUM COMPOUNDS; NIOBIUM IONS; OXIDES; SINTERING; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K; TEMPERATURE RANGE 1000-4000 K; X-RAY DIFFRACTION

Citation Formats

Thangadurai, Venkataraman, and Weppner, Werner. Effect of sintering on the ionic conductivity of garnet-related structure Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} and In- and K-doped Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}. United States: N. p., 2006. Web. doi:10.1016/j.jssc.2005.12.025.
Thangadurai, Venkataraman, & Weppner, Werner. Effect of sintering on the ionic conductivity of garnet-related structure Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} and In- and K-doped Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}. United States. doi:10.1016/j.jssc.2005.12.025.
Thangadurai, Venkataraman, and Weppner, Werner. Sat . "Effect of sintering on the ionic conductivity of garnet-related structure Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} and In- and K-doped Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}". United States. doi:10.1016/j.jssc.2005.12.025.
@article{osti_20784946,
title = {Effect of sintering on the ionic conductivity of garnet-related structure Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} and In- and K-doped Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}},
author = {Thangadurai, Venkataraman and Weppner, Werner},
abstractNote = {Garnet-structure related metal oxides with the nominal chemical composition of Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}, In-substituted Li{sub 5.5}La{sub 3}Nb{sub 1.75}In{sub 0.25}O{sub 12} and K-substituted Li{sub 5.5}La{sub 2.75}K{sub 0.25}Nb{sub 2}O{sub 12} were prepared by solid-state reactions at 900, 950, and 1000 deg. C using appropriate amounts of corresponding metal oxides, nitrates and carbonates. The powder XRD data reveal that the In- and K-doped compounds are isostructural with the parent compound Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12}. The variation in the cubic lattice parameter was found to change with the size of the dopant ions, for example, substitution of larger In{sup 3+}(r {sub CN6}: 0.79 A) for smaller Nb{sup 5+} (r {sub CN6}: 0.64 A) shows an increase in the lattice parameter from 12.8005(9) to 12.826(1) A at 1000 deg. C. Samples prepared at higher temperatures (950, 1000 deg. C) show mainly bulk lithium ion conductivity in contrast to those synthesized at lower temperatures (900 deg. C). The activation energies for the ionic conductivities are comparable for all samples. Partial substitution of K{sup +} for La{sup 3+} and In{sup 3+} for Nb{sup 5+} in Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} exhibits slightly higher ionic conductivity than that of the parent compound over the investigated temperature regime 25-300 deg. C. Among the compounds investigated, the In-substituted Li{sub 5.5}La{sub 3}Nb{sub 1.75}In{sub 0.25}O{sub 12} exhibits the highest bulk lithium ion conductivity of 1.8x10{sup -4} S/cm at 50 deg. C with an activation energy of 0.51 eV. The diffusivity ('component diffusion coefficient') obtained from the AC conductivity and powder XRD data falls in the range 10{sup -1}-10{sup -7} cm{sup 2}/s over the temperature regime 50-200 deg. C, which is extraordinarily high and comparable with liquids. Substitution of Al, Co, and Ni for Nb in Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} was found to be unsuccessful under the investigated conditions.},
doi = {10.1016/j.jssc.2005.12.025},
journal = {Journal of Solid State Chemistry},
number = 4,
volume = 179,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • Oxides with the nominal chemical compositions Li{sub 5}La{sub 3}Sb{sub 2}O{sub 12} and Li{sub 6}SrLa{sub 2}Sb{sub 2}O{sub 12} were prepared by solid-state reaction. The structures were refined by the Rietveld method using powder X-ray diffraction data. The synthesis of Li{sub 5}La{sub 3}Sb{sub 2}O{sub 12} resulted in the well known garnet-related structure plus 5 wt.% of La{sub 2}LiSbO{sub 6} in the bulk. In contrast to that, Li{sub 6}SrLa{sub 2}Sb{sub 2}O{sub 12} could be synthesised in single garnet-related type phase. Lithium ion conductivities of Li{sub 5}La{sub 3}Sb{sub 2}O{sub 12} and Li{sub 6}SrLa{sub 2}Sb{sub 2}O{sub 12} were studied by the ac impedance method. Themore » grain-boundary contribution to the total (bulk + grain-boundary) resistance is very small and about 5 and 3% for Li{sub 5}La{sub 3}Sb{sub 2}O{sub 12} and Li{sub 6}SrLa{sub 2}Sb{sub 2}O{sub 12}, respectively, at 24 deg. C and decreases further with increase in temperature. Among the investigated compounds, Li{sub 5}La{sub 3}Sb{sub 2}O{sub 12} exhibits the highest total (bulk + grain-boundary) and bulk ionic conductivity of 7.8 x 10{sup -6} and 8.2 x 10{sup -6} S cm{sup -1}, respectively, at 24 deg. C. The structural data indicate that the coupled substitution Li + Sr {yields} La leads to a closure of the bottle neck like O-O distances of the shared edges of neighbouring Li octahedra and therefore reduces the mobility of Li ions in Li{sub 6}SrLa{sub 2}Sb{sub 2}O{sub 12}. Scanning electron microscope (SEM) images of the Li{sub 6}SrLa{sub 2}Sb{sub 2}O{sub 12} compound revealed well crystallised large homogeneous grains ({approx}4.8 {mu}m) and the grains were in good contact with the neighbouring grain, which leads to a smaller grain-boundary contribution to the total resistance.« less
  • We report the single crystal structures of a series of lanthanide containing tantalates, Ln{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} (Ln=La, Pr, Nd) that were obtained out of a reactive lithium hydroxide flux. The structures of Ln{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} were determined by single crystal X-ray diffraction, where the Li{sup +} positions and Li{sup +} site occupancies were fixed based on previously reported neutron diffraction data for isostructural compounds. All three oxides crystallize in the cubic space group Ia3-bard (No. 230) with lattice parameters a=12.7735(1), 12.6527(1), and 12.5967(1) A for La{sub 3}Li{sub 5}Ta{sub 2}O{sub 12}, Pr{sub 3}Li{sub 5}Ta{sub 2}O{sub 12}, andmore » Nd{sub 3}Li{sub 5}Ta{sub 2}O{sub 12}, respectively. A UV-Vis diffuse reflectance spectrum of Nd{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} was collected to explain its unusual Alexandrite-like optical behavior. To evaluate the transport properties of Nd{sub 3}Li{sub 5}Ta{sub 2}O{sub 12}, the impedance data were collected in air in the temperature range 300{<=}T(deg. C){<=}500. - Graphical abstract: Crystal structure of garnets Ln{sub 3}Li{sub 5}Ta{sub 2}O{sub 12} (Ln=La, Pr, Nd). TaO{sub 6} polyhedra are shown in yellow and Ln{sup 3+} are shown as light blue spheres. Octahedrally and tetrahedrally coordinated Li{sup +} ions are shown in green and brown, respectively. Oxygen atoms are omitted for clarity.« less
  • We have successfully synthesized a high-purity polycrystalline sample of tetragonal Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12}. Single crystals have been also grown by a flux method. The single-crystal X-ray diffraction analysis verifies that tetragonal Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} has the garnet-related type structure with a space group of I4{sub 1}/acd (no. 142). The lattice constants are a=13.134(4) A and c=12.663(8) A. The garnet-type framework structure is composed of two types of dodecahedral LaO{sub 8} and octahedral ZrO{sub 6}. Li atoms occupy three crystallographic sites in the interstices of this framework structure, where Li(1), Li(2), and Li(3) atoms are located atmore » the tetrahedral 8a site and the distorted octahedral 16f and 32g sites, respectively. The structure is also investigated by the Rietveld method with X-ray and neutron powder diffraction data. These diffraction patterns are identified as the tetragonal Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} structure determined from the single-crystal data. The present tetragonal Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} sample exhibits a bulk Li-ion conductivity of sigma{sub b}=1.63x10{sup -6} S cm{sup -1} and grain-boundary Li-ion conductivity of sigma{sub gb}=5.59x10{sup -7} S cm{sup -1} at 300 K. The activation energy is estimated to be E{sub a}=0.54 eV in the temperature range of 300-560 K. - Graphical abstract: Garnet-related Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} having tetragonal symmetry (I4{sub 1}/acd, no.142) has been successfully synthesized. Single crystals have been also grown by a flux method. The single-crystal X-ray diffraction analysis verifies that tetragonal Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} has the garnet-related type structure with the lattice constants of a=13.134(4) A and c=12.663(8) A and the fully ordered arrangement of Li atoms.« less
  • We have successfully synthesized a polycrystalline sample of tetragonal garnet-related Li-ion conductor Li{sub 7}La{sub 3}Hf{sub 2}O{sub 12} by solid state reaction. The crystal structure is analyzed by the Rietveld method using neutron powder diffraction data. The structure analysis identifies that tetragonal Li{sub 7}La{sub 3}Hf{sub 2}O{sub 12} has the garnet-related type structure with a space group of I4{sub 1}/acd (no. 142). The lattice constants are a=13.106(2) A and c=12.630(2) A with a cell ratio of c/a=0.9637. The crystal structure of tetragonal Li{sub 7}La{sub 3}Hf{sub 2}O{sub 12} has the garnet-type framework structure composed of dodecahedral La(1)O{sub 8}, La(2)O{sub 8} and octahedral HfO{submore » 6}. Li atoms occupy three types of crystallographic site in the interstices of this framework structure, where Li(1) atom is located at the tetrahedral 8a site, and Li(2) and Li(3) atoms are located at the distorted octahedral 16f and 32g sites, respectively. These Li sites are filled with the Li atom. The present tetragonal Li{sub 7}La{sub 3}Hf{sub 2}O{sub 12} sample exhibits bulk Li-ion conductivity of sigma{sub b}=9.85x10{sup -7} S cm{sup -1} and grain-boundary Li-ion conductivity of sigma{sub gb}=4.45x10{sup -7} S cm{sup -1} at 300 K. The activation energy is estimated to be E{sub a}=0.53 eV in the temperature range of 300-580 K. - Graphical abstract: The crystal structure of tetragonal Li{sub 7}La{sub 3}Hf{sub 2}O{sub 12} had the garnet-related type structure with a space group of I4{sub 1}/acd (no. 142) with the lattice constants of a=13.106(2) A and c=12.630(2) A. The tetragonal Li{sub 7}La{sub 3}Hf{sub 2}O{sub 12} had the fully ordered Li arrangement.« less
  • The authors have synthesized two new lithium-containing oxides which are related to Ruddlesden-Popper phases, Li{sub 4}Sr{sub 3}Nb{sub 5.77}Fe{sub 0.23}O{sub 19.77} and Li{sub 4}Sr{sub 3}Nb{sub 6}O{sub 20}, with partial occupancy of the 12-coordinated sites by Sr, for the first time by direct solid-state reaction. While the single crystal and powder X-ray diffraction data indicate that these oxides crystallize in tetragonal cells (space group I4/mmm; a = 3.9585(2) {angstrom}, c = 25.915(3) {angstrom} and a = 3.953(2) {angstrom}, c = 26.041(5) {angstrom} for the respective oxides), the electron diffraction of some of the crystallites shows supercell reflections with a {approx} {radical}2a{sub p},more » c {approx} 25.9 {angstrom}, probably indicating a twisting of the NbO{sub 6} octahedra in the ab-plane. Although, these oxides show no significant lithium ionic conduction at room temperature, they show distinct conductivity values at elevated temperatures.« less