Synthesis, structural, morphological and electrical properties of NBT-BT ceramics for piezoelectric applications

In this paper, the synthesis of ferroelectric (1−x)(Na0.5Bi0.5)TiO3 (NBT)-xBaTiO3 (BT) ceramics of different compositions (x=0.07, 0.06 wt%) around the morphotropic phase boundary (MPB) by solid state reaction technique has been reported. From the Scanning Electron Microscopy (SEM) analysis, the pebble-like morphology of the synthesized ceramics has been changed to regular cube-like morphology for higher BT concentration. The phase coexistence and crystal structure have been determined by using X-ray powder diffraction. Presence of functional groups has been identified by Raman Spectroscopy at room-temperature. The dielectric properties of the ceramics were investigated in the frequency range of 200 Hz-2 MHz from room temperature to 500 °C. The broad dielectric peak and frequency dispersion demonstrate the relaxor behavior of ceramics. The dielectric constant (εr), transition temperature (Tm), depolarization temperature (Td) and diffusive factor (γ) are found to be comparatively good and tabulated for 5 kHz. The ac conductivity follows jump relaxation model at low frequency and double power at high frequency and temperature. For these ceramics P-E loops with high remnant polarization were obtained at room temperature. The d33 values for NBT-BT 94/6 and NBT-BT 93/7 were 85 and 102 pC/N respectively. The open circuit g - constants have been calculated and it is high for NBT-BT 93/7.