Sintering of nanocrystalline BaTiO3

Two-step sintering method was employed to consolidate nano-size BaTiO3 powders. The two-step sintering method comprises the initial heating at relatively higher temperatures and the following low-temperature sintering for a long period of heating. Pressed green bodies of BaTiO3 were first heated to 1300 °C to achieve an intermediate density (>75% of theoretical density), then cooled down and held at 1100 °C for 0–20 h until they became fairly dense. Slight grain growth progressed during the second step, whereas the density significantly increased. The average grain size of dense ceramics was around 1 μm. The dielectric constant of BaTiO3 was much greater than that of the normal sintering method. Furthermore, Dy-doped BaTiO3 showed much smaller grain sizes than the undoped BaTiO3, which is comparable with the conventional sintering behavior of BaTiO3.