Study on effect of cubic- and tetragonal phased BaTiO₃ on the electrical and thermal properties of polymeric nanocomposites

Polymer matrix nanocomposites based on polycarbonate (PC) and nanosized-cubic/tetragonal phases of barium titanate (BaTiO₃) were fabricated using a solution method followed by hot pressing. The content of both cubic- and tetragonal phased BaTiO₃ was varied from 0 to 50 wt%. For a given weight fraction, the dielectric constant of the nanocomposites containing tetragonal BaTiO₃ is more than those of cubic BaTiO₃ filled nanocomposites. Moreover, cubic BaTiO₃/PC nanocomposites showed significantly lower dissipation factor than those of tetragonal BaTiO₃/PC nanocomposites. The dielectric constant of the nanocomposites was found to be frequency-independent. The microhardness of the nanocomposites increased with increase in the BaTiO₃ content (both cubic- and tetragonal-phased) compared to the pure matrix. Scanning electron microscopy showed better dispersion and good interaction of the tetragonal BaTiO₃ nanoparticles in the matrix. The addition of cubic BaTiO₃ nanoparticles significantly reduced the thermal stability of the nanocomposites compared to matrix while the addition of tetragonal BaTiO₃ nanoparticles decreased it slightly. The glass transition temperature of the cubic BaTiO₃/PC nanocomposites decreased significantly, whereas it reduced slightly for the tetragonal BaTiO₃/PC nanocomposites. - Highlights: • The effect of cubic-BaTiO₃ and tetragonal-BaTiO₃ nanoparticles were studied. • Cubic-BaTiO₃ nanoparticles showed better microhardness. • Tetragonal-BaTiO₃ nanoparticles showed better dielectric and thermal properties. • Frequency independent dielectric constants of the nanocomposites were observed.