Colossal permittivity in high-entropy CaTiO₃ ceramics by chemical bonding engineering.

Abstract

Dielectrics with high permittivity, low dielectric loss, and good temperature stability are crucial for electronic components to meet the ever-increasing application demands. However, challenges remain in further optimizing dielectric properties due to the correlation between these parameters. Here, we propose a chemical bonding engineering strategy in high-entropy CaTiO₃ ceramics and realize colossal permittivity with low loss and excellent stability. Our results reveal that the high-concentration oxygen vacancy ( <math xmlns="http://www.w3.org/1998/Math/MathML"> <msubsup><mrow><mi>V</mi></mrow> <mrow><mi>O</mi></mrow> <mrow><mo>⋅</mo> <mo>⋅</mo></mrow> </msubsup> </math> )-related defects and the decreased activation energy of grain/grain boundary led to a colossal permittivity dielectric behavior, which should be ascribed to the weakened chemical bonding and the reduced formation energy of defects confirmed by our first-principles calculation. Consequently, in the high-entropy CaTiO₃ ceramic, a permittivity of 2.37 × 10⁵, low loss of 0.005, and good temperature stability (<± 15%) in -50-250 °C are simultaneously achieved. This finding implies that chemical bonding engineering may be a promising strategy for designing colossal permittivity materials and provides a broad opportunity for the development of other defect-dependent functional materials.