Microstructure and properties of Sm-substituted BiFeO3 ceramics

Bi1−xSmxFeO3 (x=0.00−0.15) ceramics were synthesized by sol-gel technique with rapid liquid phase sintering process to study the effects of samarium (Sm) substitution on their microstructure and properties. X-ray diffraction (XRD) and Raman studies showed that the structure of BiFeO3 was changed from rhombohedral to orthorhombic at the samarium substitution concentration about x=0.10. The SEM investigation suggested that the Sm substitution hindered the grain growth. Magnetic measurements showed that all the samples studied had a weak ferromagnetism, and the ferromagnetic property of BiFeO3 was improved by Sm substitution due to the suppressed or broken cycloid spin structure caused by the changes in the crystalline structure and size effect. The leakage current was found to be reduced with increasing Sm concentration. The dielectric and ferroelectric measurements showed that dielectric constant, dielectric loss and ferroelectric properties were strongly dependent on the Sm content, Sm substitution could significantly improve the dielectric constant, remnant polarization and decrease the dielectric loss due to the significant decrease of the electric leakage of the samples.