Dielectric Relaxation in Ceramics with Intragrain Concentration Gradient

We created a material with a composition gradient within each grain. Due to the graded composition the ceramic does not show a sharp change in dielectric constant near the relaxation frequency. Instead, we observe gradual decrease in dielectric constant with frequency, with the loss tangent remaining practically unchanged (below 0.02 everywhere within the frequency range 0.0003-3 GHz). The tunability of the ceramic decreases with increasing frequency but remains in the order of 10 % at 3 GHz. Thus we conclude that the dielectric relaxation in high purity (Ba,Sr)TiO3 occurs predominantly by Ti ion hopping relaxation. We also expect that the concept of intragrain concentration gradient ceramics may become a useful material for a wide range of electronic devices. PACS: 77.22.Gm, 77.22.Ch, 77.84.Dy