Sintering of nanocrystalline BaTiO3

A two-step sintering method was used to consolidate nanosize BaTiO3 powders. It comprises initial heating at relatively higher temperatures and subsequent 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 micron. 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 behaviour of BaTiO3. 21 refs.