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

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 ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup><mml:mrow><mml:mi>V</mml:mi></mml:mrow> <mml:mrow><mml:mi>O</mml:mi></mml:mrow> <mml:mrow><mml:mo>⋅</mml:mo> <mml:mo>⋅</mml:mo></mml:mrow> </mml:msubsup> </mml: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.