Relaxor behavior in BaTiO3

BaTiO3 shows relaxation effects when minute concentrations of Bi+3 and Fe+3 are added in varying molar ratios. Addition of Bi+3 at the A site reduces the transition maximum (T-m), whereas Fe+3 addition at the B site reduces t he value of dielectric constant. Doping of Bi+3 and Fe+3 in equimolar ratio s shows a positive shift in relaxation, while excess addition of either of the dopants produces a negative shift in the transition maximum with increa sing frequency. Relaxation effects follow the Vogel-Fulcher law for spin gl asses. The dielectric loss also shows relaxation effects. (C) 2000 American Institute of Physics. [S0003-6951(00)01506-0].