Effect of fluxing additive on sintering temperature, microstructure and properties of BaTiO 3

Abstract

Various fluxing materials are added to technical ceramics in an attempt to lower their sintering temperatures and make their processing economical. The effect of 0·3wt%Li 2CO 3 addition on the phase, microstructure, phase transition temperatures and dielectric properties of BaTiO 3 was investigated in the present study. The addition of 0·3wt% Li 2CO 3 was observed to lower the optimum sintering temperature by ∼200°C with no second phase formation and cause a five-fold reduction in grain size. Rhombohedral-to-orthorhombic and tetragonal-to-cubic phase transitions at the expected temperatures were evident from the Raman spectra, but the orthorhombic-totetragonal phase transition was not clearly discernible. The persistence of various phase(s) at higher temperatures in the flux-added materials indicated that the phase transitions occurred relatively slowly. A decrease in dielectric constant of Li 2O-added BaTiO 3 in comparison to pure BaTiO 3 may be due to the diminished dielectric polarizability of Li + in comparison to Ba 2+. © Indian Academy of Sciences.