Electromechanical behavior of NBT-BaTiO3 ceramics

Abstract

The prime objective of this project is to investigate electromechanical behavior of lead free (Na0.5Bi0.5)TiO3 – xBaTiO3 ceramics (NBT-BT(x)). The raw materials for formation of each ceramics were mixed and ballmilled for 24 hours and sintered at two different temperature, namely 1100oC (10hours) and 1250oC (6 hours) for NBT and BT respectively. The NBT-BT ceramics were prepared using appropriate mixture of Na0.5Bi0.5TiO3 and BaTiO3 powders with NBT-BT weight ratios of 90:10, 92:8, 94:6, 96:4, and 98:2. Then these powders were ground and uniaxially pressed at 3.68 x 103 Pa to form 13 mm diameter pellets. Next the pellets were heated for 2 hours at 700oC. Microstructures, morphology and elemental studies of the ceramics were conducted using XRD, SEM and EDX respectively. The pressure sensing behaviors were investigated using pneumatic loading method. XRD diffractograms revealed the presence of polycrystalline NBT as a major phase in all mixed samples with small quantity of BaTiO3 and Bi2Ti2O7 phases. NBT peaks progressively shift to higher diffraction intensity directions with increasing excess BaTiO3 amount. SEM micrographs showed that the NBT-BT(x) microstructure shape and size were decrease when BaTiO3 were added due to promoted no raise of microstructure densification. These samples were less influenced by the amount of BaTiO3 at the starting composition. All samples contained pores with small grain size. EDX analysis revealed that all elements Na:Bi:Ti in all samples remained unchanged when BaTiO3 were added. The additions of BaTiO3 were found significantly influenced electromechanical properties of NBT-BT ceramics.