Stable dielectric response in lead-free relaxor K0.5Na0.5NbO3–SrTiO3 thin films

K0.5Na0.5NbO3–SrTiO3 (KNN–STO) thin films of different compositions were prepared by the chemical solution deposition method. While structural investigations confirmed the formation of perovskite solid solution in all developed films, dielectric experiments revealed a relaxor broad dispersive maximum in the sample with 15 mol% of STO, exhibiting for a thin film high ε′ ~ 330 at ~ 210 K. The history-dependent effects of this relaxor sample were compared to those of KNN–STO ceramics and, furthermore, shown to be much weaker than in widely used lead-based ferroelectric and relaxor (Pb,La)(Zr,Ti)O3 ceramics: While fatigue endurance results revealed a slight drop in polarization after 3 × 105 switching cycles, the results of aging of the dielectric constant revealed no notable decrease in its values after 106 s

Stable dielectric response of low-loss aromatic polythiourea thin films on Pt/SiO2 substrate

We have investigated dielectric properties of aromatic polythiourea (ArPTU, a polar polymer containing high dipolar moments with very low defect levels) thin films that were developed on Pt/SiO2 substrate. The detected response is compared to the response of commercially available polymers, such as high density polyethylene (HDPE) and polypropylene (PP), which are at present used in foil capacitors. Stable values of the dielectric constant ε′≈5 (being twice higher than in HDPE and PP) over broad temperature and frequency ranges and dielectric losses as low as in commercial systems suggest ArPTU as a promising candidate for future use in a variety of applications