Unconventional upright layer orientation and considerable enhancement of proton–electron conductivity in Dion–Jacobson perovskite thin films
Excimer-laser-assisted metal organic deposition is a straightforward process for growing uniaxially oriented Dion–Jacobson perovskite thin films. We have confirmed that on amorphous glass substrates, Dion–Jacobson phases normally crystallize and become oriented with layer-stacking ordering, for example, in RbLa2Ti2NbO10 and RbLaNb2O7 thin films under KrF laser irradiation. Here, we observed a unique orientation in RbCa2Nb3O10 thin films, where almost perfect upright layered structures were realized on amorphous glass substrates. The precursor RbCa2Nb3O10 thin film crystallized in uniaxial (100)-orientation under KrF laser irradiation with a fluence above 100 mJ cm−2 and with a preference for (100)- and (001)-orientations below 100 mJ cm−2. The obtained (100)-oriented RbCa2Nb3O10 thin films showed an extremely high proton–electron conductivity of 4.9 × 10−2 S cm−1 at 400 °C.