Synthesis procedure and effect of Nd, Ca and Nb doping on structure and electrical conductivity of Li7La3Zr2O12 garnets

Procedure of solid state synthesis of Li7La3Zr2O12 garnets was investigated. After calcination of reactants at 800 °C single-phased tetragonal-structure garnet material was produced. Subsequent sintering at 1200 °C gave cubic-structure garnet. The effect of Ca, Nd and Nb doping for structure parameters and Li-ion conductivity was studied. Ca and Nd dopants were located in La sublattice, whereas Nb was located in Zr sublattice, leading to changes in nominal lithium content. Similarly to nominally undoped Li7La3Zr2O12, all doped materials possessed cubic garnet structure, however, in all the cases the observed lattice parameters were lower than for the undoped material. For all synthesized materials, determined lithium content was lower than the nominal value, and slight amount of aluminum was detected. Electrical conductivity at room temperature for all tested materials was in the range 0.8–4.2 × 10− 5 S cm− 1. Nearly linear positive correlation between lattice constant and ionic conductivity was observed. The influence of lithium variation for the studied composition range was found to be insignificant.