Effect of total pressure on La2NiO4 coatings deposited by reactive magnetron sputtering using plasma emission monitoring

This work focuses on the structural, microstructural, electrical and electrochemical characterization of La-Ni-O coatings deposited by reactive magnetron sputtering under different argon partial pressures. Deposition was driven by Plasma Emission Monitoring system (PEM) which allows high deposition rate. For each pressure, the optimal regulation setpoint for lanthanum oxide deposition is determined and then the current dissipated on the nickel target is adjusted to obtain the convenient La/Ni ratio to achieve the K2NiF4 structure. After an appropriate annealing treatment, coatings crystallize in the desired structure with more or less impurities. Increasing the device's pressure from 0.4 to 4.8 Pa produces more porous samples with different microstructures. Then, a coating with porosity gradient was built by using these four different total pressures. Its electrical performances were tested and allowed its utilization as cathode layer in intermediate temperature-solid oxide fuel cell (IT-SOFC). This modified architecture cathode allows better performances (71 mW·cm− 2) than dense cathode produced by the same technique (51 mW·cm− 2).