High-Entropy Design of Perovskite Quantum Paraelectrics with Improved Dielectric Properties in GHz and THz Bands

High Resolution Image Download MS PowerPoint Slide High-entropy engineering offers a promising pathway to enhance dielectric permittivity at elevated frequencies in perovskite oxides by increasing compositional complexity. Here, two titanate-based high-entropy quantum paraelectrics, (Ba 0.2 Sr 0.2 Ca 0.2 La 0.2 Na 0.2 )TiO 3 (BSCLN) and (Ba 0.2 Sr 0.2 Ca 0.2 La 0.2 K 0.2 )TiO 3 (BSCLK) were developed via entropy-driven phase stabilization, and their dielectric responses were systematically investigated from radiofrequency to terahertz regimes. Both materials exhibit spatially distributed local polar modes arising from entropy-induced configurational local polar disorder (LPD) and entropy-enhanced lattice-coupled local polar fluctuation (LPF). In the radiofrequency range, weak- and strong-field permittivity are nearly identical, with the strong-field permittivity remaining ∼ 250, indicating a dominant ionic polarization contribution and excellent dielectric stability. Negative extrapolated Curie temperatures (<0 K), together with the temperature-dependent permittivity behavior, confirm the quantum paraelectric nature of both compositions. In the microwave regime, the high-entropy quantum paraelectrics show significantly higher dielectric permittivity (∼155–189) and lower dielectric loss (∼0.002) compared to BaTiO 3 and SrTiO 3, while their terahertz response is governed by entropy-enhanced local polar fluctuations. These results demonstrate that combining high-entropy design with quantum paraelectric functionality provides an effective strategy for developing high-frequency dielectric materials for next-generation electronic devices.