Preparation And Characterization Of Samarium Doped Strontium Titanate

Perovskite oxide is an important kind of inorganic compounds as functional materials. SrTiO₃, as a typical perovskite oxide,is widely used in electronic and mechanical applications for its low dielectric loss and thermal stability. And it can be made into high and middle voltage ceramic capacitors, boundary layer ceramic capacitors and low voltage dependent resistors. SrTiO₃ can also be used in producing hydrogen, degrading polluted organic and photochemical cells Because of its high band gap (312eV) and photo-catalysis activity.At present, ABO₃ oxides doped with rare element in A or B sites become one of hotspots. Sm doped SrTiO₃, a mixed conductor, shows high conductivity, high catalysis activity, good chemical and good thermal stability, This makes it potentially be used as anode materials for solid oxide fuel cells. The powder is usually made by solid-state reaction.The powders is coarse size, poor activity, and a high sintering temperature manufactured by the solid-state reaction.In this dissertation, Sr_1-1.5xSm_xTiO₃ was made by a novel wet chemical way of gel-casting. The effect of Sm content and sintering temperature on phase, powders morphology, particle size and sintering activity were investigated, and the properties of the sintered specimen as-prepared were also tested. The results showed the powders made by gel-casting showed uniform particle size and good properties. Sm content and sintering temperature had greatly affected the phase of powders. The powders sintered at 1200°C with 4mol% Sm doped showed pure perovskite and 1.77μm in size, and Sr_1-1.5xSm_xTiO₃ sintered at 1400°C showed high porosity and mechanical strength. Sm doped into SrTiO₃ evidently improved conductivity, and the conductivity tested in hydrogen was higher than that tested in air. The conductivity of Sr_0.94Sm_0.04TiO₃ sintered at 1400°C in hydrogen and air were 28.2 S·cm^-1 and 0.0041 S·cm^-1 at 800°C, respectively. Sm also made Sr_0.94Sm^0.04TiO₃ show a high Rockwell hardness of 91.5HRA and high bend strength of 825.32MPa.