ChemInform Abstract: Synthesis, Crystal Chemistry, and Electrochemical Properties of Li_7‐2xLa₃Zr_2‐xMo_xO₁₂ (x = 0.1—0.4): Stabilization of the Cubic Garnet Polymorph via Substitution of Zr⁴⁺ by Mo⁶⁺.

Abstract

Li7‐2xLa3Zr2‐xMoxO12 (x = 0.1—0.4) are prepared by calcining a stoichiometric mixture of Li2CO3, La2O3, ZrO2, and MoO3 (850 °C, 4 h), followed by grinding and final sintering (1230 °C, 4 h).

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

“…In these spectra, there is no indication of interface or grain boundary effects, which would cause a second semicircle in the Nyquist plots. 12 When the blocking electrode is represented by another constant phase element, the circuit in Figure 6A results, which allows excellent fits of all data (see Figure 6A).…”

“…These are realistic values for oxides and support the interpretation of the arc as a bulk property. 12 Therefore, resistance R 1 can be used to determine the Li-ion conduction in the bulk by…”

Synthesis, Crystal Structure, and Stability of Cubic Li7–xLa3Zr2–xBixO12

“…In general, the obtained spectra show a good coincidence with other spectra of cubic LLZO stabilized with different aliovalent cations. 16,19,43,49,50 In addition to the characteristic LLZO bands, additional bands at 156, 195, and 1090 cm −1 were observed for all samples. These bands can be assigned to Li 2 CO 3 .…”

“…The band at ∼590 cm −1 gets more intense and slightly shifts to lower wavenumbers with increasing Bi content, whereas at the same time the intensity of the band at ∼650 cm x O 12 , as they observed the appearance and intensity increase of a band at ∼770 cm −1 with increasing Mo content of the garnet. 16 The evolution of the Raman spectra of LLZBO can be explained similarly. The progression of the band at 590 cm −1 is considered as an effect of the extended bond length of Bi−O bonds in comparison to Zr−O bonds, as the ionic radius of Bi 5+ is larger than that of Zr 4+ , resulting in the appearance of a band at smaller wavenumbers, which slightly shifts to lower wavenumbers with increasing Bi contents, in accordance with the slightly increasing unit-cell parameters of the LLZBO samples with increasing Bi contents.…”

“…1,3 Since the Li ion conductivity of the cubic phase is at least 2 orders of magnitude higher (10 −4 to 10 −3 S cm −1 at room temperature) in comparison to the tetragonal phase, the stabilization of the cubic phase at room temperature is highly needed. 3−5 Fortunately, the cubic polymorph can be stabilized at room temperature by doping with supervalent cations such as Al 3+ , 2,5−8 Fe 3+ , 9,10 and Ga 3+ , 11−14 which are incorporated on the 4-fold coordinated 24d/96h positions replacing Li + , Ce 4+ replacing La 3+ on the 8-fold coordinated 24c position, 15 and Mo 6+ , 16,17 Nb 5+ , 18 Ta 5+ , 12,13,19−21 Sb 5+ , 22 Te 6+ , 23 W 6+ , 24 and Y 3+25 replacing Zr 4+ at the octahedrally coordinated 16a position. It was recently shown by Xia et al that a stabilization of the cubic Ia3̅ d modification can also be achieved by a partial substitution of Zr 4+ with Bi 5+ ; the end member Li 5 La 3 Bi 2 O 12 (LLBO) was already described by Murugan et al and further discussed in several other studies.…”