Barium titanate nanoparticles produced by planetary ball milling and piezoelectric properties of corresponding ceramics

Barium titanate (BaTiO3) nanocrystalline powders were prepared by solid state reaction route starting from BaCO3 and TiO2 powders accompanied by high-energy ball milling. Different samples were prepared by varying the milling time from 1 h to 30 h, keeping the milling speed fixed at 250 rpm. All the milled powders were examined with TEM. The particle size first decreases from 105 nm to a minimum of 28 nm as the milling time increases from 1 h to 20 h and then increases to 38 nm with further increase of milling time to 30 h. Dense ceramics were formed by sintering the nanopowders at 1350 °C for 4 h. With decreasing particle size of the starting nanopowders, the ceramics exhibit gradual increase in density from 5.65 g/cc to 5.84 g/cc, coercive field (Ec) from 2.25 kV/cm to 4.77 kV/cm and piezoelectric charge constant (d33) from 99pC/N to 121pC/N.

Research Highlights► BaTiO3 nanopowders with 105–28 nm particle size were produced by high-energy milling. ► Increasing milling time from 1 h to 20 h reduces the particle size from 105 nm to 28 nm. ► Further increase from 20 h to 30 h increases the particle size from 28 nm to 38 nm. ► Prevailing theories fail to explain the increase in particle size with milling time. ► Changes in Ec and d33 for the resulting ceramics corroborate the observed phenomenon.