Boosting energy storage performance in negative temperature coefficient linear-like dielectrics via composite modulation in the superparaelectric state

Developing dielectric ceramics with both negative temperature coefficient of capacitance (NTCC) and excellent energy storage performance is beneficial to obtain multifunctional dielectric ceramic capacitors. An effective strategy of composite modulation in the superparaelectric (SPE) state is proposed in BaTiO3-BaZrO3-CaTiO3 (BT-BZ-CT) system to achieve the above two points. The simultaneous addition of BZ and CT to BT ferroelectrics can move the SPE state to the normal use temperature zone and the NTCC characteristic with enhanced energy storage performance can be obtained; and the intentional precipitation of CT at grain boundaries can refine the grain size, increase the bandgap, and strengthen the local electric field distribution as well, thus enhancing the breakdown electric field (Eb). Benefiting from these features, EIA class I-R3L code NTCC together with a high Wrec (~3.46 J/cm3) and η (90.8%) were achieved in 20BT-40BZ-40CT system, providing a paradigm for building NTCC dielectric materials with high energy-storage performance.