Structural, dielectric and transport properties of samarium-doped cobaltites

Abstract

Cobaltites have gained considerable importance in the field of material science, due to their valuable dielectric, biological and magnetic properties. This work highlights the importance of samarium (Sm) doping to enhance the structural and dielectric properties of bismuth calcium cobaltite. All samples were synthesized using the co-precipitation technique and were sintered at 750 °C for 2 h. X-Ray Diffraction (XRD) analyses, as well as Fourier-transform infrared spectroscopy, are used to realize the monoclinic structure of all samples. In addition, XRD analysis was used to determine the lattice strains, lattice constant, crystallite size, the volume of a unit cell, and dislocation density. This analysis shows that Sm doping increases the dislocation density and lowers the average crystallite size. The AC conductivity, (σac), dielectric constant (ε), and loss tangent tan (δ) for all samples were measured at various fixed frequencies and in the variable frequency range (100Hz – 3 MHz). The obtained results are also discussed using the non-linear modified Debye function and Jonscher's power law. The composition Bi2Ca1.95Sm0.05CoO6 proves to be the better dielectric material at 350 °C–600 °C as it achieves a high value for dielectric constant while maintaining the lower dielectric loss than that of other compositions. Bi2Ca1.95Sm0.05CoO6 acquires a higher value for σac than the previously reported σac values of Ca2-xYxCo2O5. These qualities make the aforementioned specimen highly preferable for energy applications.