Two-step sintering of ceramics with constant grain-size, II:: BaTiO3 and Ni-Cu-Zn ferrite

We investigated the preparation of bulk dense nanocrystalline BaTiO3 and Ni-Cu-Zn ferrite ceramics using an unconventional two-step sintering strategy, which offers the advantage of not having grain growth while increasing density from about 75% to above 96%. Using nanosized powders, dense ferrite ceramics with a grain size of 200 nm and BaTiO3 with a grain size of 35 nm were obtained by two-step sintering. Like the previous studies on Y2O3, the different kinetics between densification diffusion and grain boundary network mobility leaves a kinetic window that can be utilized in the second-step sintering. Evidence indicates that low symmetry, ferroelectric structures still exist in nanograin BaTiO3 ceramics, and that saturation magnetization is the same in nanograin and coarse grain ferrite ceramics.