Low temperature dielectric relaxation in complex perovskite BaTi0.8(Ni0.5Nb0.5)0.2O3 ceramics

Structure and dielectric properties of complex perovskite BaTi0.8(Ni0.5Nb0.5)0.2O3 ceramics have been investigated by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) and dielectric spectroscopy. XRD and Raman data show that the BaTi0.8(Ni0.5Nb0.5)0.2O3 ceramics have a superstructure unit cell with Fm3¯m space group. The dielectric characteristics in the 175-250 K region are confirmed to be an incipient ferroelectric response with frequency dependent relaxation, which is attributed to the NiNi3+2+′-VO·· dipolar defect.