INFLUENCE OF PARTICLE SIZE AND SINTERING TEMPERATURES ON ELECTRICAL PROPERTIES OF 0.94Na(0.5)Bi(0.5)TiO(3)-0.06BaTiO(3) LEAD FREE CERAMICS

Abstract

In this study, lead-free 0.94 Na0.5Bi0.5TiO3-0.06BaTiO(3) (NBT-BT) compositions at morphotropic phase boundary were successfully synthesized by solid-state reaction method. The effects of the particle size for various milling time (12-24-48 hours) and sintering temperatures (1100-1125-1150-1175 degrees C for 2h) on the electrical properties of the NBT-BT ceramics were evaluated. Experimental results showed that particle size and sintering temperatures significantly affect the electrical properties of NBT-BT ceramics. The particle size of the ceramic powders decreasing while milling time increases to 48 hours. Particle size values for 0, 12, 24 and 48 hours (h) milled powders were measured as nearly 1.5 mu m, 1 mu m, 700 nm, and 500 nm respectively. The bulk density enhanced with increasing sintering temperature and showed the highest value (5.73 g/cm(3)) at 1150 degrees C for 48h milled powder. Similarly, the maximum piezoelectric constant (d(33)) = 105 pC/N, electromechanical coupling coefficient (k(p)) = 25.5% and dielectric constant (K-T) = 575 were measured at 1150 degrees C for 48 h milled powder. However, mechanical quality factor (Q(m)) was reduced from 350 to 175 with decreasing particle size. Similarly, remnant polarization was dropped by decreasing powder particle size from 56 mu C/cm(2) to 45 mu C/cm(2).