Ionic Conductivity Investigation in Undoped and La-doped Potassium-Strontium Germanate K<sub>4</sub>SrGe<sub>3</sub>O<sub>9</sub>
<i>The double germanate K</i><sub><i>4</i></sub><i>SrGe</i><sub><i>3</i></sub><i>O</i><sub><i>9</i></sub><i> was selected as prospective cation conductor using geometric analysis of potassium-containing oxides. The solid solution formation with heterovalent substitution of lanthanum for strontium was investigated. Possible lanthanum positions and point defects configuration were tested using atomistic simulation. Ionic conductivity of ceramics in dry air at 300 °С is 4,3·10</i><sup><i>-3</i></sup><i> S/m for K</i><sub><i>4</i></sub><i>SrGe</i><sub><i>3</i></sub><i>O</i><sub><i>9</i></sub><i> and 1,01·10</i><sup><i>-2 </i></sup><i>S/m for K</i><sub><i>3,8</i></sub><i>Sr</i><sub><i>0,8</i></sub><i>La</i><sub><i>0,2</i></sub><i>Ge</i><sub><i>3</i></sub><i>O</i><sub><i>9</i></sub><i></i>