Dielectric properties with high dielectric permittivity and low loss tangent and nonlinear electrical response of sol-gel synthesized Na1/2Sm1/2Cu3Ti4O12 perovskite ceramic

Abstract

Giant dielectric ceramic, Na1/2Sm1/2Cu3Ti4O12, was successfully prepared by a modified sol-gel method. X-ray diffraction experiments indicated that a body-centered cubic structure with a space group of Im3 was obtained. Our density functional theory calculations revealed that codoping Na and Sm in the CaCu3Ti4O12 structure resulted in charge compensation between Na and Sm ions in this structure, whereas the oxidation states of Cu and Ti were unaltered. Giant dielectric permittivity ∼7.21 × 103 - 8.04 × 103 and low dielectric loss tangent ∼0.045–0.049 were accomplished at a sintering temperature of 1050 °C for 12–18 h. Nonlinear J - E property with breakdown electric field ∼5.13 – 5.78 × 103 V/cm and nonlinear coefficient ∼6.08–6.82 were also achieved. The n-type semiconducting grain originated from short-range migrations of mixed Cu+/Cu2+ and Ti3+/Ti4+ charges. Finally, our charge analysis showed that the occurrence of Cu+ and Ti3+ was related to the existence of oxygen vacancy in these ceramics.