Interfacial proton conduction in high-dielectric-constant spinel-perovskite NiFe2O4–LaFeO3 nanocomposite probed by impedimetric humidity sensing

The impedimetric humidity sensing is used to establish the interfacial proton conduction in spinel-perovskite NiFe 2 O 4 –2LaFeO 3 (NFO-2LFO) nanocomposite that exhibited a contrasting combination of high dielectric constant and high AC conductivity. The inter-grain/grain boundary resistance of NFO-2LFO exhibited a systematic decrease with increasing relative humidity (RH) revealing humidity-dependent proton conduction that occurs primarily at the interfaces than at intra-grain/bulk regions. The observed proton conduction at the grain boundaries/interfacial regions can be due to the change in the polarization of the space charge layers.