Enhanced dielectric relaxation and low-electric-field energy storage properties of NaNbO3 ceramics prepared by co-doping MgO and BiYbO3

NaMg 0.12 Nb 0.88 O 3 - x BiYbO 3 (abbreviated as NMN- x BY) ( x  = 0, 0.005, 0.01, 0.015, 0.02, 0.04 and 0.08) ceramics were fabricated by using a traditional solid-state reaction method. The crystal structure, morphology, relaxation behavior and energy storage properties of NMN- x BY) ceramics were systematically investigated. X-ray diffraction patterns (XRD) demonstrates that all samples present a single pseudo-cubic phase. It is also found that the grain sizes vary irregular with the BY content, and it can be reduced by the appropriate addition of BY content as indicated by scanning electron morphology. From the measured dielectric properties , it can be seen that all samples are transformed from normal ferroelectric (FEs) to relaxor ferroelectric (RFEs). The maximum relaxor diffuseness coefficient γ (∼1.78) is obtained for 0.98NMN-0.02BY ceramic. As x increases, the polarization-electric ( P - E ) hysteresis loops gradually become slimmer. The largest discharged energy density (∼0.998 J/cm 3 ) and the maximum energy efficiency (∼70%) are obtained at 170 kV/cm for x  = 0.04. Meanwhile, the discharge energy densities present relatively excellent temperature stability for x  = 0.02 in the temperature range from 20 to 140 °C. This work demonstrates a wide potential application in enhancing the storage properties of lead-free ferroelectric materials by co-doping MgO and bismuth-based perovskites .