Bottle-necked ionic transport in Li 2 ZrO 3 : high temperature neutron diffraction and impedance spectroscopy

Nonstoichiometry and Li‐ion transport in lithium zirconate: The role of oxygen vacancies

“…In the previous conductivity studies of LZO, the final sintering was carried out either in O 2 or in inert gas (i.e., He), whereas the effect of atmospheres on phase stability and electrical properties of LZO were unclear. Figure A compares XRD patterns of samples sintered in 3 different atmospheres with 5 wt% Li excess.…”

“…Based on the XRD full‐pattern fittings (using GSAS software) lattice parameters are a = 5.412 Å, b = 9.008 Å, c = 5.409 Å, β = 112.695° for LZO‐Ar (Figure B), and a = 5.422 Å, b = 9.022 Å, c = 5.419 Å, β = 112.690° for LZO‐O 2 (Figure A). The lattice parameters extracted for the powder obtained after calcination at 950°C/10 h in air and before final sintering (Figure B) are a = 5.421 Å, b = 9.025 Å, c = 5.418 Å, and β = 112.699°, which are very close to those of LZO‐O 2 and are consistent with reported values . Unlike LZO‐O 2 , the LZO‐Ar sample showed shrinkage in lattice size after sintering.…”

“…The electronic contribution for both samples is < 1%. The activation energy and conductivity values of our LZO‐Ar sample are comparable with those reported by Sherstobitova et al However, several differences should be noted. The LZO‐Ar sample in this study exhibit negligible grain‐boundary resistance compared to the bulk resistance, whereas the reported sample shows blocking grain boundaries (σ ion, bulk ≈ σ ion, g.b ) as can be seen in Table .…”

“…This is consistent with the reported lower relative density (69%) when compared with that (83%) of our sample. In addition, we do not observe an obvious jump‐like transition from ionic to superionic conduction at around 467°C, which is suggested to be caused by redistribution of lithium ions over Li1 and Li2 lattice sites at elevated temperatures . The jump‐like behavior is closely related to the Li deficiency in Li 2 ZrO 3 ‐type compounds, which can largely be affected by synthesis method and the heat‐treatment protocol .…”

“…Previous experimental and computational studies have shown that Li + hopping through vacant sites is responsible for Li + migration in LZO. Generally, a higher lithium vacancy concentration would lead to higher Li + conductivity and lower migration barrier . Oxygen vacancies, while less studied, are another source of ionic defects in LZO.…”