▎ 摘　　要

The present work reports on the synthesis characterization of Ca(Co-1.5-Ni-0.5)Y-type ferrite/GO nanocomposites with 10, 20 and 30 wt% of GO named as C-1, C-2 and C-3, respectively, via ultrasonication technique. The Co-Ni doped Ca-ferrite (Ca2Co1.5Ni0.5Fe12O22) was prepared via sol-gel technique sintered at 900 degrees C for 5 h, and graphene oxide (GO) was prepared by modified Hummer's method. The structural features and physical properties of the composites were studied by X-ray diffraction, dielectric and electrical measurements. XRD results confirmed the phase formation of Y-type hexaferrite and formation of GO, while the XRD pattern of composites is similar to the pattern of pure Y-type ferrite indicating that restacking of graphene sheets is prevented and ferrite particles are homogenously dispersed on the surface of the graphene oxide sheets. The pure GO exhibits the largest value of dielectric constant (1 x 10(6)) at lower frequency range. The dielectric measurement showed that concentration of GO in composites directly related to dielectric constant. The composite with 30 wt% loading of GO has maximum dielectric constant (25 x 10(3)) in all composites. It is observed that DC resistivity of composites at room temperature decreased from 12.4 x 10(8) to 0.96 x 10(8) ohm-cm with increasing GO concentration. It was observed that resistivity of Y-type ferrite/GO composites decreased with increasing temperature, which indicate the semiconducting nature of composites. The value of activation energy decreased from 0.283 to 0.031 eV with increasing GO concentration in composites, which is consistent with resistivity results.