High temperature dielectric response in Sm3Fe5O12 ceramics

• High dielectric permittivity is observed in Sm3Fe5O12 ceramic.
• Two types of dielectric relaxations are observed.
• The concentration of Fe2+ influences the relaxation process.

Polycrystalline Sm3Fe5O12 ceramics are synthesized by a sol–gel method. High temperature dielectric properties in the frequency range from 100 Hz to 10 MHz are investigated at different temperatures from 300 to 800 K. This material exhibits high dielectric permittivity and low dielectric loss in a wide range of temperature and frequency. The contribution of electrode polarization to the dielectric permittivity is ruled out by the dc bias voltage measurement at room temperature. Two types of dielectric relaxations are clearly observed, and both of them are thermal activated relaxations following the Arrhenius law. The high frequency relaxation is shown to originate from the carrier hopping between Fe2+ and Fe3+, while the low frequency relaxation most likely arises from the conduction. The concentration of Fe2+ is proved to influence the low frequency dielectric relaxation.