Bottle-necked ionic transport in Li2ZrO3: high temperature neutron diffraction and impedance spectroscopy

We present a study of the crystal structure, ionic conductivity and Li migration map in a wide temperature range for the Li2ZrO3 and Li1.8ZrO3-δ samples synthesized by the solid state reaction and soft chemistry methods, respectively. Both samples were found to be Li-deficient at room temperature with the partially vacant Li[1] sites. Thermally activated redistribution of Li+ ions between two lithium sites has been revealed by high temperature neutron diffraction. The redistribution of lithium results in rise of the ionic conductivity and drop of the activation energy observed on the AC conductivity data at the temperatures above 740 K for Li2ZrO3 and 710 K for Li1.8ZrO3-δ. It has been found that more deficient Li1.8ZrO3-δ sample prepared by the soft chemistry method exhibits enhanced ionic conductivity. Three-dimensional lithium migration map composed of the stripe-like migration pathways has been constructed. Most of the elementary channels composing lithium migration map were found to be probabilistic ones, which indicates bottle-necked ionic transport in both compounds.