Influence of grain refinement on the dielectric properties of B-site doped BaTiO3-based high-entropy ceramics

The dielectric performance of BaTiO 3 -based ceramic capacitors must be improved for further miniaturization and integration of energy storage devices. This study combines two optimization strategies, the grain refinement and high-entropy effect, to design BaTiO 3 -based high-entropy nanocrystalline ceramics: Ba(Ti 0.2 Zr 0.2 Nb 0.2 Y 0.2 Sn 0.2 )O 3 (HEO1) and Ba(Ti 0.2 Zr 0.2 Nb 0.2 Yb 0.2 Hf 0.2 )O 3 (HEO2). These ceramics were synthesized using fast hot-pressing sintering (FHPS), yielding HEO1-FHPS and HEO2-FHPS samples, both of which exhibit a pure perovskite structure, similar to that of samples fabricated via conventional solid-state sintering (CS), namely HEO1-CS and HEO2-CS. The relative densities of the HEO1-FHPS (96.18 %) and HEO2-FHPS (98.34 %) samples are higher than those of HEO1-CS (95.47 %) and HEO2-CS (95.40 %). In addition, the grain sizes of HEO1-FHPS (0.092 μm) and HEO2-FHPS (0.084 μm) are notably smaller than those of HEO1-CS (2.48 μm) and HEO2-CS (2.91 μm). The high relative density and small grain size of HEO1 and HEO2 improve their maximum permittivity, increase the Curie temperature and enhance dielectric stability. Furthermore, compared with HEO1-CS and HEO2-CS, HEO1-FHPS and HEO2-FHPS exhibit higher critical electric field strengths (359 and 389 kV/cm), greater recoverable energy densities (0.40 and 0.88 J/cm 3 ) and improved energy storage efficiencies (69.6 % and 70.4 %). These findings provide a promising approach for developing BaTiO 3 -based ceramics with enhanced dielectric performance.