Relaxor ferroelectric behaviour observed in (Ca0.5Sr0.5Ba0.5Pb0.5)Nb2O7 perovskite layered structure ceramics

Relaxor ferroelectric behaviour was observed in perovskite layered structure (PLS) (Ca0.5Sr0.5Ba0.5Pb0.5)Nb2O7 (CSBPN) ceramics engineered using the high entropy approach. The CSBPN ceramics were sintered at 1350 degrees C and are single-phase with an orthorhombic structure (Cmcm space group) at room temperature. Their relaxor ferroelectric behaviour is characterized by a broad and frequency-dependent permittivity maximum and a cur-rent peak around zero electric field in the hysteresis loop. The presence of polar nanoregions is supported by piezoresponse force microscopy images. The value of the relative permittivity epsilon ' = 130 at 1 kHz and room temperature is much larger than that for conventional PLS ceramics Sr2Nb2O7 (epsilon ' = 42) and Ca2Nb2O7 (epsilon ' = 38). This can be attributed to the presence of polar nanoregions and the lattice distortion effect in high entropy materials. The appealing dielectric and relaxor behaviour of CSBPN ceramics confirms the efficacy of the high entropy approach to obtain improved properties.