Enhanced conductivity of (110)-textured ScSZ films tuned by an amorphous alumina interlayer

Herein a novel strategy to tune the crystallite orientation and the ionic conductivity of solid electrolyte films through interfacial control has been reported. 10 mol% Sc2O3-doped ZrO2 (10ScSZ) thin films were prepared with an amorphous alumina (AO) interlayer (AO/10ScSZ) using magnetron sputtering. It has been found that a (110)-preferred orientation develops in AO/10ScSZ films annealed at 1000 °C due to a strong interfacial interaction, while 10ScSZ films deposited without the AO interlayer are (111)-textured. The (110)-oriented AO/10ScSZ films show an ionic conductivity nearly 4 times higher than that of the (111)-oriented 10ScSZ films. This is explained by the fact that the (110)-texture provides faster migration pathways with lower energy barrier for oxygen vacancies. These results reveal the relationship between the crystal structure and the conductivity of AO/ScSZ heterostructured films, which can facilitate the development of high-performance multilayered electrolytes and enable the miniaturization of solid-state electrochemical devices operable at temperatures below 600 °C.