Achieving simultaneously low loss tangent and high resistivity in MgO modified Sr0.979Y0.014TiO3 colossal-permittivity ceramics via inhibiting the diffusion of oxygen vacancies

Abstract

Colossal permittivity (CP, Ɛr) ceramics are highly desired for promising applications in modern electronic industry. However, actual applications of CP ceramics were seriously limited by large dielectric loss(tanδ), strong temperature/frequency/electric field dependence, and resistance degradation behavior. Here, we proposed a novel strategy to inhibit the diffusion of oxygen vacancies to obtain a CP Sr0.979Y0.014TiO3 (SYT14) ceramic with a combination of low tanδ and high insulation resistivity (ρ), by MgO addition, due to the formation of [MgTi″−VO••], [MgTi″−2YSr•] and highly insulated phase at the grain boundary. SYT14-7M (x = 0.7 wt% MgO) ceramic has excellent comprehensive properties, such as, Ɛr is 28156, tanδ is 0.0136, and ρ is 7.02 × 1011 Ω•cm. The phenomenon of “resistance oscillation” reflects the active degree of oxygen vacancy diffusion behavior. The highly insulated phase forming at the grain boundary can significantly inhibit oxygen vacancy diffusion and electron migration. The temperature range related to active oxygen vacancy diffusion is between 400 and 500 °C.