NBT based ceramics

Introduction about Na_0.5Bi_0.5TiO₃ (NBT)

Pb(Zr,Ti)O₃ (PZT) based ferroelectric materials have been widely used in electronic applications for their piezoelectric and dielectric properties. But, lead based materials cause health and environmental problems. So, lead based materials are being replaced by lead-free ceramic materials.

The Na_0.5Bi_0.5TiO₃ (NBT) based lead-free ceramic materials are widely investigated, for composition based morphotropic phase boundary or polytrophic phase transition to achieve dielectric and piezoelectric properties. Na_0.5Bi_0.5TiO₃ (NBT) is a well known ABO₃ perovskite ceramic with a ferroelectric rhombohedral phase at room temperature. As temperature increases, the phase of NBT transforms from rhombohedral to tetragonal and finally into cubic phase.

NBT is expected to replace the lead based piezoelectric ceramics due to the presence of morphotrophic phase boundary - for some NBT based ceramics exhibit relatively higher piezoelectric properties than single phased NBT compound. To improve their piezoelectric properties, various dopants and novel ceramics processes have been used in preparing NBT based lead-free ceramic materials like,

Na_0.5Bi_0.5TiO₃-SrTiO₃

Na_0.5Bi_0.5TiO₃-BaSrTiO₃

Na_0.5Bi_0.5TiO₃-BaZrO₃

Na_0.5Bi_0.5TiO₃-SrTiO₃-BaTiO₃

Finally, the Na_0.5Bi_0.5TiO₃ based lead-free ceramics are being prepared by solid state reaction method. The prepared samples will be characterized by PXRD,UV-Visible spectroscopy, SEM, EDS and electrical studies like dielectric, piezoelectric and ferroelectric and the crystal structure and charge density distribution of the prepared samples will analyzed by maximum entropy method (MEM).