The influence of the partially europium substitution on the AC electrical properties of BiSr2CaCu2O6.5 ceramics

In this work, EuxBi1-xSr2CaCu2O6.5 (where x = 0, 0.3, 0.5) samples were prepared by solid-state reaction method and sintered at 950°C for 24 h. The structural characterizations were done by X-ray diffraction, X-ray fluorescence, scanning electron microscope and Fourier transformed infrared spectroscopy. The thermal stability of the samples was also analysed by thermogravimetric TG and DTA measurements. It was shown that Eu0.5Bi0.5Sr2CaCu2O6.5 sample exhibited high dielectric constant and low dielectric loss relative to BiSr2CaCu2O6.5 material. Thus, the dielectric loss was lowered by heavy rare earth metal substitution on Bi-Sr-Ca-Cu-O ceramics while the dielectric constant still remained high. Temperature-dependent complex electrical modulus spectra obtained between 296 and 433K also revealed the temperature-activated relaxation process in the materials which can be attributed to the Maxwell-Wagner type polarization effect. Ultimately, it was suggested that the Eu0.5Bi0.5Sr2CaCu2O6.5 ceramics may have a promising potential for applications which require high dielectric constant with a low dielectric loss.