Effect of mechanical milling on the structural and dielectric properties of BaTiO3 powders

Barium titanate (BaTiO3) is a well-known ferroelectric material and widely used in electronic industries for the multi-layer ceramic capacitor. In this reported work, commercially available tetragonal BaTiO3 (BT) powders were taken to study the size effect on the structural and dielectric properties of the BT ceramics during high-energy ball milling (0-110 h). The same perovskite when kept under a normal atmospheric condition after milling shows gradual increase of additional crystalline phase that occurred because of the absorption of atmospheric CO2 gas, which is characterised as orthorhombic BaCO3. The milled BT samples were characterised by X-ray diffraction and small-angle X-ray scattering and a dielectric analyser. The purpose of this work was to study how the dielectric property of nanoBT ceramics varies with reduction of particle size, structural changes and the absorption of carbon by these nanopowders. It was observed that the dielectric constant of the BT powders increases with particle size reduction during milling. The dielectric behaviour of the BT ceramics significantly changes with polymorphic phase transformation in nanocrystalline BT at different stages of milling. The capacitance of nanoBT powders is significantly changed with the absorption of carbon by the nanoBT powders in a humid atmosphere.