LAUSR

Lead free relaxor 0.8NBT-0.2BT nano-structured ceramic composition was processed through sol-gel technique and sintered at 1140°C for 4 h in air. The bulk density exceeded 95% of theoretical density as determined by Archimedes principle. The sintered samples were characterized using X-ray diffraction, field emission scanning electron microscope, energy dispersive spectrometry, Raman, dielectric, AC impedance, piezoelectric and ferroelectric measurements. XRD patterns recorded at room temperature confirmed the rhombohedral phase formation of the samples. Particle size range measured for calcined powder was found to be of 40-50 nm and the average grain size of the final sintered sample was 80 nm. Analysis of Raman spectral data of the sample indicated distortion of NBT. The diffuse phase transition behaviour was investigated from ε versus T curve and the temperature due to structural change coincided with abrupt jump in ε(T) curve. Dielectric maximum and minimum were also evaluated to define phase transitions of 0.8NBT-0.2BT system. NBT-BT has shown normal diffuse type of phase transition. Charge transformational behaviour could be analyzed based on AC and DC conductivity measurements. Ferroelectricity was also confirmed by P-E measurements and piezoelectric constant obtained for the NBT-BT sample was 90 pC/N. GRAPHICAL ABSTRACT