Kinetics and thermodynamics of intracrystalline Fe-Ga distribution in Y3(Fe, Ga)5O12

Nitsche, R.; Tippelt, Gerold; Amthauer, Georg

doi:10.1007/bf01117599

Cited by 7 publications

(4 citation statements)

References 26 publications

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“…The most intense Fe 3+ doublet with an area, A , of 79% has an isomer shift δ =0.20 mm/s and a quadrupole splitting of Δ E Q =0.96 mm/s. These values are similar to the isomer shift and quadrupole splitting values of Fe 3+ at the 24 d tetrahedral position in natural silicate and certain synthetic garnets (i.e., Y 3 (Fe,Ga) 5 O 12 ), namely, δ =0.20 mm/s and Δ E Q =0.98 mm/s [16,17] . Therefore, this doublet in the spectrum of Fe-bearing LLZO is assigned to Fe 3+ at the 24 d site.…”

Section: Resultssupporting

confidence: 79%

The solubility and site preference of Fe3+ in Li7−3Fe La3Zr2O12 garnets

Rettenwander

Geiger

Tribus

et al. 2015

Journal of Solid State Chemistry

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A series of Fe3+-bearing Li7La3Zr2O12 (LLZO) garnets was synthesized using solid-state synthesis methods. The synthetic products were characterized compositionally using electron microprobe analysis and inductively coupled plasma optical emission spectroscopy (ICP-OES) and structurally using X-ray powder diffraction and 57Fe Mössbauer spectroscopy. A maximum of about 0.25 Fe3+ pfu could be incorporated in Li7−3xFexLa3Zr2O12 garnet solid solutions. At Fe3+ concentrations lower than about 0.16 pfu, both tetragonal and cubic garnets were obtained in the synthesis experiments. X-ray powder diffraction analysis showed only a garnet phase for syntheses with starting materials having intended Fe3+ contents lower than 0.52 Fe3+ pfu. Back-scattered electron images made with an electron microprobe also showed no phase other than garnet for these compositions. The lattice parameter, a0, for all solid-solution garnets is similar with a value of a0≈12.98 Å regardless of the amount of Fe3+. 57Fe Mössbauer spectroscopic measurements indicate the presence of poorly- or nano-crystalline FeLaO3 in syntheses with Fe3+ contents greater than 0.16 Fe3+ pfu. The composition of different phase pure Li7−3xFexLa3Zr2O12 garnets, as determined by electron microprobe (Fe, La, Zr) and ICP-OES (Li) measurements, give Li6.89Fe0.03La3.05Zr2.01O12, Li6.66Fe0.06La3.06Zr2.01O12, Li6.54Fe0.12La3.01Zr1.98O12, and Li6.19Fe0.19La3.02Zr2.04O12. The 57Fe Mössbauer spectrum of cubic Li6.54Fe0.12La3.01Zr1.98O12 garnet indicates that most Fe3+ occurs at the special crystallographic 24d position, which is the standard tetrahedrally coordinated site in garnet. Fe3+ in smaller amounts occurs at a general 96h site, which is only present for certain Li-oxide garnets, and in Li6.54Fe0.12La3.01Zr1.98O12 this Fe3+ has a distorted 4-fold coordination.

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Section: Resultssupporting

confidence: 79%

The solubility and site preference of Fe3+ in Li7−3Fe La3Zr2O12 garnets

Rettenwander

Geiger

Tribus

et al. 2015

Journal of Solid State Chemistry

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“…The most intense Fe 3+ doublet with an area, A, of 79 % has an isomer shift δ = 0.20 mm/s and a quadrupole splitting of ΔE Q = 0.96 mm/s. These values are similar to the isomer shift and quadrupole splitting values of Fe 3+ at the 24d tetrahedral position in natural and synthetic garnets (Y 3 (Fe,Ga) 5 O 12 ), i.e., δ = 0.20 mm/s and ΔE Q = 0.98 mm/s (Amthauer et al, 1986;Nitsche et al, 1994). Therefore, this doublet in the spectrum of Fe-bearing LLZO is assigned to Fe 3+ at the 24d site.…”

Section: Site Distribution Of Fe ( 57 Fe Mößbauer Spectroscopy)supporting

confidence: 79%

Crystal chemistry of "Li7 La3 Zr2 O12" garnet doped with Al, Ga, and Fe: a short review on local structures as revealed by NMR and Mößbauer spectroscopy studies

Rettenwander

Wagner

Langer

et al. 2016

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Cubic Li 7 La 3 Zr 2 O 12 (LLZO) garnets stabilized by substitution of Li by supervalent cations (Al 3+ , Ga 3+ and Fe 3+) are exceptionally well suited to be used as protecting layer to enable Li-metal based battery concepts. On the one hand this dopants are needed to provide the outstanding properties of LLZO at room temperature (RT), but on the other hand dopants occupying Li sites are suspected to hinder the long-range Li-ion transport properties within the structure. This depends on the type of dopant species and their amount in the LLZO garnet. In particular, the way these dopants can be distributed in the garnet structure is thought to play a critical role in the Li-diffusion behaviour. This short review addresses the difficulty to obtain structural information on minor amounts of cations in a large complicated structure such as LLZO by diffraction methods and the advantages of the application of complementary spectroscopic methods, such as Mößbauer and NMR spectroscopy, which provide information on the valence state and the distribution of the dopants Al, Ga, and Fe over the possible cation positions of the garnet structure. Finally, (i) NMR spectroscopy at very high magnetic fields (21.1 T) shows that Al and Ga are similarly distributed over the 24d and 96h sites in the garnet structure and (ii) Mößbauer spectroscopy proves that Fe occurs in the trivalent state, also at the 24d and 96h sites of the cubic garnet framework. The solubility limit of Fe, Al, and Ga is up to 0.25 pfu, 0.39 pfu, and 0.72 pfu, respectively.

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“…For LLZO and other garnet-like materials, similar values have been interpreted as tetrahedrally coordinated Fe 3+ on the 24d site. 13,14,25,26 Under consideration of the results of SC-XRD, the results of 57 Fe Moßbauer spectroscopy obtained by this study are interpreted as Fe 3+ on the Li1 (12a) and Li2 (12b) sites of LLZO:Fe with SG I4̅ 3d. As the quality of the obtained spectra is comparatively poor, the quantitative interpretation of the Moßbauer spectra must be treated with caution.…”

Section: Resultsmentioning

confidence: 67%

Fast Li-Ion-Conducting Garnet-Related Li_7–3xFe_xLa₃Zr₂O₁₂ with Uncommon I4̅3d Structure

et al. 2016

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Fast Li-ion-conducting Li oxide garnets receive a great deal of attention as they are suitable candidates for solid-state Li electrolytes. It was recently shown that Ga-stabilized Li7La3Zr2O12 crystallizes in the acentric cubic space group I4̅3d. This structure can be derived by a symmetry reduction of the garnet-type Ia3̅d structure, which is the most commonly found space group of Li oxide garnets and garnets in general. In this study, single-crystal X-ray diffraction confirms the presence of space group I4̅3d also for Li7–3xFexLa3Zr2O12. The crystal structure was characterized by X-ray powder diffraction, single-crystal X-ray diffraction, neutron powder diffraction, and Mößbauer spectroscopy. The crystal–chemical behavior of Fe3+ in Li7La3Zr2O12 is very similar to that of Ga3+. The symmetry reduction seems to be initiated by the ordering of Fe3+ onto the tetrahedral Li1 (12a) site of space group I4̅3d. Electrochemical impedance spectroscopy measurements showed a Li-ion bulk conductivity of up to 1.38 × 10–3 S cm–1 at room temperature, which is among the highest values reported for this group of materials.

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Kinetics and thermodynamics of intracrystalline Fe-Ga distribution in Y3(Fe, Ga)5O12

Cited by 7 publications

References 26 publications

The solubility and site preference of Fe3+ in Li7−3Fe La3Zr2O12 garnets

The solubility and site preference of Fe3+ in Li7−3Fe La3Zr2O12 garnets

Crystal chemistry of "Li7 La3 Zr2 O12" garnet doped with Al, Ga, and Fe: a short review on local structures as revealed by NMR and Mößbauer spectroscopy studies

Fast Li-Ion-Conducting Garnet-Related Li_7–3xFe_xLa₃Zr₂O₁₂ with Uncommon I4̅3d Structure

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Kinetics and thermodynamics of intracrystalline Fe-Ga distribution in Y3(Fe, Ga)5O12

Cited by 7 publications

References 26 publications

The solubility and site preference of Fe3+ in Li7−3Fe La3Zr2O12 garnets

The solubility and site preference of Fe3+ in Li7−3Fe La3Zr2O12 garnets

Crystal chemistry of "Li7 La3 Zr2 O12" garnet doped with Al, Ga, and Fe: a short review on local structures as revealed by NMR and Mößbauer spectroscopy studies

Fast Li-Ion-Conducting Garnet-Related Li7–3xFexLa3Zr2O12 with Uncommon I4̅3d Structure

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Fast Li-Ion-Conducting Garnet-Related Li_7–3xFe_xLa₃Zr₂O₁₂ with Uncommon I4̅3d Structure