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Na1/2Eu1/2Cu3Ti4O12 and Na1/2Sm1/2Cu3Ti4O12 dielectric ceramics were synthesized at different sintering temperatures (950, 975 and 1000 °C) by a solid-state reaction method. Phase structure, cation valence state, and dielectric properties of all sintered ceramics were systematically investigated. When the preparation temperature was changed, the Cu+ ion concentration of (Na+, Eu3+) co-doped ceramics changed faster than that of (Na+, Sm3+) co-doped ceramics. Abnormally high dielectric constants of ~ 3.17 × 104 and ~ 1.06 × 104 (at 10 Hz and 303 K) were achieved in Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 ceramics prepared at 950 °C, respectively. However, Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 prepared in high sintering temperature (1000 °C) exhibited a good frequency stability of dielectric permittivity. It was demonstrated that an increasing number of charge carriers induced by the increase of sintering temperature could lead to a competitive coexistence of two polarization mechanisms (surface barrier layer capacitor and internal barrier layer capacitor), further changing the dielectric properties of CaCu3Ti4O12-based ceramics. [ABSTRACT FROM AUTHOR]

The double peroskite Lu 2 NiMnO 6 was synthesized by a facile hydrothermal method. X-ray power diffraction (XRD) analysis shows it adopts monoclinic structure with space group P2 1 /n , indicating an ordered arrangement at B sites. Valence states analysis done by XPS shows Ni 2+ /Mn 4+ configuration. Raman spectrum reveals an ordered structure in the sample, in agreement with the XRD results. The degree of ordering was greatly enhanced after the sample was annealed at 873 K. Magnetism of the as-grown and annealed samples was analyzed using DC and AC magnetization, as well as Magnetization-Hysteresis. Dielectric anomaly independent on frequency was observed close to the magnetic ordering temperature, indicating the possibility of ferroelectricity and further magnetoelectric coupling. [ABSTRACT FROM AUTHOR]