Combined experimental and theoretical study of the low temperature dielectric and magnetic properties of trivalent Eu ion doped SrTiO_3 ceramics

摘要

Single-phase Sr_(1-3x/2)Eu_xTiO_3 (SETO_x)(x = 0-0.075) ceramics were prepared to study the effects of Eu substitution on their crystal structure, low temperature dielectric, and magnetic behaviors. Rietveld refinement of X-ray diffraction data yields direct evidence that the Eu ion substitutes Sr site at the perovskite. The measured dielectric properties can be well explained by the mean-field model. It has been found that the anomaly dielectric enhancement behavior exists in the SETO_(x=0.005) sample, while more stable quantum paraelectric states are obtained in other doped samples. On the other hand, all the Eu doped samples exhibit doping concentration dependence of paramagnetism. Developing the linear response model, we conclude that a molecular field is acting on Eu ions possibly via the spin polarized Eu-O-Ti hybridization.