Structures and colossal dielectric behavior of Na1/3Ca1/3La1/3Cu3Ti4O12 ceramics fabricated via a sol-gel process

The dielectric response of a novel giant dielectric ceramic with good dielectric and electrical properties, Na1/ 3Ca1/3La1/3Cu3Ti4O12, was investigated in this work. This ceramic, with a perovskite-like structure, was successfully synthesized using a sol-gel method. Fine-grain ceramics were found in all sintered specimens. These ceramics produced large dielectric permittivities, 9.89 x 103-1.04 x 104, and low dielectric loss tangent values of 0.040-0.057. First-principles calculations indicated that Na+ is substituted at the Cu2+ sites. Additionally, La3+ likely occupies Ca2+ sites. Experimental and computational techniques demonstrated the presence of an oxygen vacancy in the Na1/3Ca1/3La1/3Cu3Ti4O12 lattice that results in generation of Cu+ and Ti3+. The IBLC phenomenon and small polaron hopping between valence electrons of Cu and Ti ions have been recognized as the causes of the giant dielectric behavior of these materials.

Automated summary

The dielectric response of a novel giant dielectric ceramic, Na1/3Ca1/3La1/3Cu3Ti4O12, with good dielectric and electrical properties was investigated. This perovskite-like ceramic was synthesized using a sol-gel method and exhibited large dielectric permittivities and low dielectric loss tangent values. Na+ substituted the Cu2+ sites, while La3+ likely occupied Ca2+ sites. The presence of an oxygen vacancy in the lattice resulted in generation of Cu+ and Ti3+, which caused the giant dielectric behavior of these materials through the IBLC phenomenon and small polaron hopping.