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A novel system of lead-free X8R BaTiO 3 -based dielectric materials with high dielectric constants was prepared via conventional mixing method. The phase structure, dielectric and electrical properties and the “relaxorlike” characteristic of ceramic materials were systemically studied. The XRD results indicate that no secondary phase formed in the CaZrO 3 -doped samples after sintering. SEM micrographs reveal that the grain size of CaZrO 3 -doped BaTiO 3 -based samples are not uniform, ranging from 0.2 to 0.9 µm. Bulk densities and dielectric properties were measured as a function of CaZrO 3 concentration. The Curie temperatures of all CaZrO 3 doped samples increase due to the existence of an internal stress between grain cores and shells caused by the diffusion of CaZrO 3 . The oxygen vacancies have a profound effect on the dielectric loss and frequency characteristics. The 3.5 wt% CaZrO 3 -doped sample sintered at 1250 °C showed the optimal dielectric performance ( ε r =4330, tan δ <1.5%, Δ C / C 20 °C ≤±14%) that satisfied EIA-X8R specification. [ABSTRACT FROM AUTHOR]

An ultrahigh-temperature X – R type dielectric material, BaTiO 3 –Na 0.5 Bi 0.5 TiO 3 –Nb 2 O 5 –ZnO–Glass with Sm 2 O 3 addition, was successfully prepared. The effects of Sm 2 O 3 content on the phase structure, dielectric and electric properties of ceramics were investigated. Sm ion can substitute for both Ti and Ba-sites, which leads to the decrease of spontaneous polarization and dipolar polarization. As a result, the temperature stability in ε r of sample is improved obviously. The 0.2 mol% Sm 2 O 3 -doped sample shows the optimal dielectric properties ( ε r =2458; tan δ =1.80%; ∆ C / C 20 °C <±15%, −55 °C to 450 °C), which satisfies EIA X – R specification. This material with particular focuses on enhancing the upper temperature limit to 450 °C, while still maintaining high dielectric constant. [ABSTRACT FROM AUTHOR]

A lead-free, high-permittivity and high-temperature X–R type dielectric material was successfully prepared in ZnO-doped BaTiO 3 -Na 0.5 Bi 0.5 TiO 3 -Nb 2 O 5 (BNN)- based system. The effects of ZnO content on the phase structure, electric and dielectric properties of the ceramics were investigated. Results indicate that ZnO addition plays a critical role in increasing permittivity and improving the temperature stability. The 5 wt% ZnO-doped sample shows the optimal dielectric performance ( ε r =2404; tanδ=1.76%; ΔC/C 20 °C <±13%) that satisfies EIA X-R specification. In particular, the ceiling working temperature is significantly enhanced from 200 °C to 375 °C and the permittivity is increased to 2404 by doping ZnO. These results suggest that these materials are promising candidates for preparing miniaturized ultra-broad temperature multilayer ceramic capacitors. [ABSTRACT FROM AUTHOR]