Characteristic behaviour of spontaneous polarization and dielectric constant of barium titanate containing cobalt ions

The temperature dependence of the dielectric constant and the spontaneous polarization as well as the effect of their thermal history has been investigated for BaTiO₃ crystals doped with Co. Experimental evidence for diffuse phase transitions (DPT) is found. Results are interpreted taking into account that in the crystal exists a relatively large amount of disorder which can be pictured as a change in the local configuration of substituted Co-ions.