Grain Growth and Electric Properties of Lead-Free BaTiO₃ Ceramics

Many lead-free materials, such as Bi-based compounds, BaTiO3 or alkaline niobate compound, have been intensively studied. The microstructure and characteristics of BaTiO3 ceramics are significantly influenced by addition of 4PbO-B2O3. Under low sintering temperatures, the grain growth of BaTiO3 ceramic is enhanced by capillary action, rearrangement and solution-reprecipitation of the liquid phase. At high sintering temperatures, exaggerated grain growth of BaTiO3 ceramic is restrained by the presence of a liquid phase. The theory of grain growth in the presence of a liquid phase is examined in terms of the equation Rn = k× t. The grain growth kinetic exponent, n, has an inverse relationship with the rate of grain growth. With suitable amounts of glass frit and an optimized sintering temperature, the density is enhanced and the values of the dielectric and piezoelectric properties are improved.