Effect of nickel addition on the physicochemical properties of SrTiO3-based materials

Synthesis of materials in Ni/SrTiO3 system was undertaken. Perovskite structure material with nominal composition SrTi0.98O3 was synthesised by the sol-gel method. Nickel was introduced into the system by the wet impregnation method followed by proper thermal treatment. Two research paths were carried out: the evaluation of sintering conditions on material properties (sintering temperature: 1100, 1200, 1300 and 1400 degrees C; sintering time: 1, 3 and 5 h for sintering at 1300 degrees C) and the effect of nickel addition on the material properties - 1, 2, and 5 mol% of Ni compared to the amount of Ti was introduced into the analysed system. The microstructures of the materials, together with their structural (XRD analysis) and electrical (total conductivity and Seebeck coefficient) properties, were determined. Furthermore, temperature-programmed reduction (TPR) and temperatureprogrammed oxidation (TPOx) measurements were performed to evaluate the materials' redox properties. It was shown that less than 1 mol% of Ni could be incorporated into the strontium titanate structure when a wet impregnation was chosen as the method for the introduction of Ni into the SrTiO3-based system. NiO and, for the highest amount of introduced nickel, also NiTiO3 were the main additional nickel-containing phases. For all materials synthesised in the Ni/SrTiO3 system, the positive value of the Seebeck coefficient was observed, suggesting that nickel is an acceptor-type dopant while incorporated into the perovskite structure. However, the TPR measurements clearly imply that nickel can be incorporated into the strontium titanate structure in various oxidation states.

Automated summary

Materials in the Ni/SrTiO3 system were synthesized and the effects of sintering conditions and nickel addition on material properties were investigated. The results demonstrated that a small amount of nickel could be incorporated into the perovskite structure, and nickel can exist in various oxidation states within the strontium titanate structure.