Disordered ferroelectrics: BaxSr1−xTiO3 single crystals

The dielectric constant and the spontaneous polarization of crystals in the system BaxSr1xTiO (x = 0.38, 0.32, 0.26, and 0.2) are measured down to 80 °K. The transition becomes more and more diffused when x decreases, a fact which cannot be explained easily if one assumes a simple model of the local transition temperature. The polarization does not exhibit any anomaly at the transitions between ferroelectric phases contrary to the dielectric constant. It is concluded that the measuring electric field can turn easily the spontaneous polarization. in a large temperature interval.