Microstucture, dielectric properties and impedance analysis of NaBi_xTi₆O_12.5+1.5x lead-free ceramics

Lead-free NaBi_xTi₆O_12.5+1.5x ceramics (x = 0.98, 0.99, 1.01, 1.02) with a pseudo-perovskite structure were prepared via the traditional solid-phase reaction. The structure, dielectric properties and impedance spectroscopy of the NaBi_xTi₆O_12.5+1.5x ceramics were investigated in detail. X-ray diffraction patterns reveal that all of the prepared ceramics have a single phase and the scanning electron microscope confirms the well-growth performance of the ceramics. The dielectric constant and dielectric loss show great stability with a wide temperature range. It can be learned that the resistance, the maximum Debye peak, and the corresponding capacitance simultaneously decrease with increasing temperature by analysing Z* plots. The active energy of the NaBi_xTi₆O_12.5+1.5x ceramics (x = 0.98, 0.99, 1.01, 1.02) are respectively 0.67, 0.56, 1.34 and 1.37 eV, meanwhile, there is no phase transition point in 25–750 °C. The results demonstrate that the electrical properties of the NaBi_xTi₆O_12.5+1.5x lead-free ceramics can be well tuned by varying the Bi quantity.