Performance of Ca_1-xSr_xTiO₃ as barriers in dielectric barrier discharges with different Sr content

Plasma assisted catalytic technology, which uses synergetic technologies between the catalyst and plasma, has attracted much attention over the past several years. Theoretically, permittivity of a dielectric barrier influences the transferred charge of a microdischarge; thus high permittivity can improve the plasma reaction in a dielectric barrier discharge (DBD) plasma reactor. Despite the increased interest in the chemical processes, very little has been reported concerning the influence of materials of a dielectric barrier on DBD plasma reactions, since a high permittivity barrier generally exhibits low fracture strength and low dielectric strength making it break down under strong current pulses. In the present study, Ca_1-xSr_xTiO ₃ (0.1 ≤ x ≤ 0.4) which possesses a high permittivity and a high fracture strength was prepared by liquid phase sintering and was used as a dielectric barrier for the destruction of carbon dioxide by a DBD plasma reaction. The permittivity of Ca_1-xSr_xTiO₃ (0.1 ≤ x ≤ 0.4) increased with increasing SrTiO₃ content; however, the observed CO₂ conversion became greatest using Ca _0.8Sr_0.2TiO₃ and then decreased with increasing SrTiO₃ content. These results imply that the reactivity of CO ₂ destruction does not monotonously increase with increased permittivity of the Ca_1-xSr_xTiO₃ barriers. Both amplitude and density of the current pulses ignited by Ca_0.8Sr _0.2TiO₃ were much greater than that of Ca _0.6Sr_0.4TiO₃. Further, it was confirmed that a plasma reaction uniformly proceeded using the Ca_0.8Sr _0.2TiO₃ barrier, but proceeded non-uniformly using the Ca_0.6Sr_0.4TiO₃ barrier by observing the carbon deposition profiles on the surfaces of the barriers.