Nb‐doped 0.9BaTiO3–0.1Bi0.5Na0.5TiO3 (0.9BT–0.1BNT) ceramics were prepared by conventional solid‐state method. The dielectric and the structural properties were investigated. It was found that the temperature–capacitance characteristics greatly depended on Nb2O5 content. With the addition of 2.0 mol% Nb2O5, 0.9BT–0.1BNT ceramic sample could satisfy the EIA X9R specification. This material was promising for high‐temperature MLCC application. Microstructure element distribution was studied using TEM and EDS. The Bi and Na were almost homogeneously distributed except grain‐boundary segregation of Bi. The Nb exhibited a nonuniform distribution from the grain boundary to the interior, showing the simultaneous presence of Nb‐rich and Nb‐poor regions. Such microheterogeneity gave rise to the temperature stability of permittivity. The solution‐precipitation mechanism was introduced to elucidate the evolution of microstructures. Degradation and recovery of insulation resistance were observed under a dc bias at 200°C, which was attributed to the electromigration and diffusion of Na+.

0.9BaTiO3–0.1Bi0.5Na0.5TiO3‐based (0.9BT–0.1BNT) ceramics with Tc = 180°C were prepared using a novel chemical coating method. The relationships among compositions, microstructures, and properties were investigated. TEM morphologies displayed the Nb‐coated powders, which were confirmed by energy dispersive spectroscopy (EDS). Temperature‐dependence of permittivity for Nb‐modified 0.9BT–0.1BNT ceramics measured at different frequencies showed no relaxor characteristic at high temperature, but frequency dispersion at low temperature. The microstructures were characterized by two types of grains: Nb‐rich grains and Nb‐free grains, which were responsible for temperature‐stable dielectric properties. The sample with 5 mol% Nb addition satisfied the X9R specification. The permittivity was 1934 and the dissipation factor was 1.53% at room temperature.

Effects of CaZrO3 on BaTiO3–MgO–MnO2–Y2O3 nonreducible ceramics were investigated. The specimens modified by CaZrO3 in the range from 0 to2 mol% were prepared via conventional mixing method. Transmission electron microscopic analysis revealed that doping elements were enriched at grain boundaries and “core–shell” structures were formed. The addition of CaZrO3 could lower the sintering temperature. The Curie temperature was shifted to a higher point with increasing CaZrO3, attributed to the existence of an internal stress produced by lattice mismatch between grain cores and shells. Temperature dependence of dielectric constant and capacitance change were also dependent on CaZrO3 content. With the increasing of CaZrO3 content, the insulation resistivity was improved whereas the degradation under direct current electrical field was significant. Therefore, a proper CaZrO3 content is crucial to obtain high performance X8R nonreducible BaTiO3‐based dielectrics.

Lead titanate nanotube arrays were in‐situ grown by hydrothermal synthesis. The hydrothermal process is time‐dependent and in different hydrothermal reaction stages, different growth mechanisms dominate the formation of PbTiO3 nanotubes. In the initial stage in‐situ growth of PbTiO3 nanotube arrays dominates. Subsequently dissolution–precipitation process dominates and results in the deposition of PbTiO3 particles on the surface of the already‐formed PbTiO3 nanotubes. In order to in‐situ grow PbTiO3 nanotube arrays with perfect nanotubular structure, suitable hydrothermal reaction time should be applied.

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