Electromechanical behavior of NBT-BaTiO₃ ceramics

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 1100⁰C (10hours) and 1250⁰C (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 700⁰C. 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.