Hua Hao

The semiconducting phenomenon of BaTiO3 induced by sintering in reducing atmospheres is the key bottleneck restricting its application in high-performance base metal electrode multilayer ceramic capacitors (BME-MLCCs). In this work, a surface modification strategy was innovatively developed via defect regulation to improve the reduction resistance of ceramic powders. A Ba-rich component (Ba/Ti = 1.02) was coated onto 100 nm BaTiO3 powders using the sol–gel method, denoted as BT@x(1.02) (x = 0–1.0). As x increases, the concentration of oxygen vacancies in ceramics sintered in a reducing atmosphere is significantly reduced, accompanied by a substantial increase in resistivity. Complex impedance spectroscopy analysis indicates that an increase in the coating amount significantly enhances the conductivity activation energies of both grains and grain boundaries. High strain was observed near the grain boundaries of BT@1.0 (1.02) ceramics. Electron energy loss spectroscopy (EELS) analysis indicated that this strain originated from the non-uniform distribution of the Ba/Ti ratio. From the grain boundary to the interior of the grain, the Ba/Ti ratio gradually decreases, and the polarization intensity increases accordingly. Furthermore, EELS results reveal oxygen enrichment at 200 nm from the grain boundary. Based on first-principles calculations, it is inferred that such oxygen originates from the grain interior, and the defect layer prevents oxygen from diffusing out of the grains, thereby enhancing the reduction resistance of the ceramic. This study provides a strategy for the development of high-performance reduction-resistance BaTiO3 ceramics.

We combined feature selection and SHAP analysis to identify promising composition ranges, then used EGO to guide synthesis. Four new compositions were prepared and characterized, yielding superior ε _r25 in just one experimental round.

Ceramic-polymer nanocomposites combine the respective advantages of ceramics and polymers, boasting superior mechanical flexibility, thermal stability, optical transparency, and electrical conductivity, enabling their wide use in cutting-edge fields like medicine, aerospace, optoelectronic devices, and energy storage components. Notably, ceramic-polymer nanocomposites are a promising, widely recognized strategy for developing high-energy-density, low-dielectric-loss, and flexible capacitors, due to the ceramic phase’s intrinsic high dielectric constant, which enhances dielectric capability, and the polymer phase’s high breakdown strength and mechanical flexibility. Ultimately, ceramic-polymer nanocomposites can reach an optimal dielectric performance. In this study, polyvinylidene fluoride (PVDF) was used as the matrix material and barium titanate (BaTiO₃) as the reinforcing phase within the composite structure. The BaTiO₃ ceramic particles were incorporated into PVDF via spin-coating technology, with composite formulations prepared at different concentrations (0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%). A series of key parameters were measured and compared, such as the dielectric constant, breakdown strength, and energy storage density, of the BT/PVDF nanocomposite. The results indicated that the BT/PVDF nanocomposite with the optimal low BaTiO₃ content demonstrates remarkable performance, achieving a breakdown strength (E_b) of 500 MV/m and an effective energy storage density of 15.5 J/cm³. This represents an improvement over conventional uniformly high-filler films.