fig3

Figure 3. Temperature and the ac field dependence of the dielectric constant of a BaTiO₃ ceramics with a grain size of 1.2 mm. The ac field frequency was 100 Hz. The peaks in the permittivity correspond to the phase transition in BaTiO₃; on increasing temperature, the material transforms from a rhombohedral ferroelectric to an orthorhombic ferroelectric to a tetragonal ferroelectric to a paraelectric cubic structure.