Reduced dielectric loss in new colossal permittivity (Pr, Nb)TiO2 ceramics by suppressing adverse effects of secondary phases.

Here, we develop new colossal permittivity (CP) (Pr0.5Nb0.5)xTi1-xO2 ceramics by controlling the secondary phases, and then both colossal permittivity (εr = 6-8 × 104, 1 kHz) and low dielectric loss (tan δ = 3.7-7.5%, 1 kHz) can be realized in a composition range (x = 0.5-2.5%). The ceramics with x = 1% possess a high dielectric constant (εr = 74 533), and importantly a low dielectric loss (tan δ = 3.7%) can be found, which is lower than most of the typical CP materials and chemically modified TiO2 ceramics. In addition, the εr changing rates of 143 per degree Celsius and 35 per kiloHertz indicate an excellent temperature and frequency stability of the dielectric behaviors. XRD, FE-SEM and element mapping are conducted to probe the secondary phases, and element line scanning is used to explore the elemental composition of the secondary phases. The test results indicate that optimized dopants can enhance the dielectric properties, while secondary phases induced by x > 5% dopants can cause adverse effects on the dielectric properties. XPS results further demonstrate that the defect-dipole theory may be suitable to explain the significant improvement of dielectric properties. We believe that (Pr, Nb)TiO2 ceramics are one of the most competitive candidates in the field of electronic and energy-storage devices.