Synthesis and oxygen transport properties of La2 − ySryNi1 − xMoxO4 + δ

La2NiO4 + δ-based materials (LN) with tetragonal K2NiF4-type structure exhibit high electronic and oxygen ion conductivity. In this work synthesis, phase relations and oxygen transport properties are reported for the system La2 − ySryNi1 − xMoxO4 + δ where 0.0 ≤ y ≤ 0.4 and 0.0 ≤ x ≤ 0.1. The solubility of Mo in LN is low, but becomes enhanced by Sr substitution on the A-site. La1.8Sr0.2Ni0.95Mo0.05O4 + δ (LSNM) bar shaped samples were subjected to electrical conductivity relaxation (ECR) for assessment of oxygen bulk diffusion (Dchem), oxygen surface exchange (kchem) and electronic conductivity. The p-type conductivity was 50 S·cm− 1 at 900 °C, which is lower than both LN and LSN (Sr = 0.2). On the other hand, kchem was enhanced by one order of magnitude compared with LN at all temperatures, while Dchem was lower at T > 700 °C and higher at T < 700 °C