Epitaxial stabilization and tunable oxygen stoichiometry of R32 BaNiO3-x thin films via pulsed laser deposition

Abstract Metastable materials can exhibit functionalities that outperform the ground state if stabilization routes can be identified. The metastable R 32 phase of barium nickelate (BNO) has been proposed to have increased catalytic activity, but the structure-stoichiometry-property relationship has not been established. This study develops routes to stabilize the R 32 phase of BNO by determining the impact of pulsed laser deposition (PLD) processing parameters on the stoichiometric tunability and stability of R 32 BNO. (100)-oriented R 32 BNO thin films were stabilized on (0001) Al 2 O 3 substrates at a substrate temperature of 400 °C and oxygen partial pressures ranging from 9.1 × 10 –2 mbar to 1.27 × 10 –2 mbar. This work elucidates the stoichiometric tunability and conductivity of R 32 BNO, providing the critical insight needed to advance the application of BNO in catalysis, gas sensing, and lead-free piezoelectrics. Graphical abstract