Loss mechanisms and domain stabilisation in doped BaTiO3

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Abstract
The ferroelectric and dielectric properties of La, Sr, Zr, Fe and Mn doped BaTiO3 ceramic are measured within wide limits of the amplitude Eapproximately of the external electrical AC field. At sufficiently low Eapproximately the losses are not ferroelectric in origin but are rather determined by the low frequency relaxational response of the material, which is influenced by doping. In the ferroelectric phases a well defined threshold Eapproximately 0 exists at any composition such that the permittivity and the loss factor are independent of Eapproximately for Eapproximately Eapproximately 0 due to domain wall motions and reversal of the spontaneous polarisation Ps.Eapproximately 0 is less than 20 V cm-1 in La doped BaTiO3 and is up to 5000 V cm-1 in Fe or Mn doped samples. Compositions with large Eapproximately 0 show constricted hysteresis loops which are described by an internal bias field Ei. In Mn doped BaTiO3 both Eapproximately 0 and Ei are increased by annealing at low partial pressures of oxygen, Ei and Eapproximately 0 are a measure of the stability of the domain configuration established during ageing below the temperature of the para-electric to ferro-electric phase transition.