X-ray photoelectron spectroscopy and electrical properties studies of Nb-doped strontium titanate ceramics prepared from titanyl acylate precursors

Abstract

Through a sol-gel or sol-precipitation process Nb 2 O 5 -doped SrTiO 3 was obtained from titanyl acylate precursors in acidic or alkaline solution, respectively. Nonstoichiometric powders were obtained by varying the Sr/Ti ratio in the starting materials. X-ray photoelectron spectroscopy (XPS) was used to investigate the surface properties of the powders and the sintered bulk ceramics. Excess Ti in the sol-gel process was converted to TiO 2 (rutile) after calcination. In contrast, in the sol-precipitation process, the excess Ti was converted to Magnéli phases, which benefited the powders sinterability, and also enhanced the formation of Ti 3+ on the powder surface, resulting in an abnormally high dielectric constant. The excess Sr in the sol-gel process was converted to SrCO 3 and then to gaseous CO 2 during sintering, which resulted in some cavities in the microstructure. In the sol-precipitation process, a structure of Sr n+1 Ti n O 3n+1 was established and some near rectangular shaped, high-density grains were obtained.

Sulfur-tolerant cobalt-doped La0.3Sr0.7TiO3-d-perovskite cathode for intermediate-temperature solid oxide electrolysis cell

“…Approximately 4.1 eV higher than the metal oxygen peak, the third oxygen peak is observed to have binding energy of 533.4 eV. A surface-adsorbed carbonate species is thought to be related to this peak [50,[57][58][59][60]. Oxygen species can be divided in to the lattice oxygen (O lattice ) and adsorbed oxygen (O adsorbed ) [57,61].…”

“…A surface-adsorbed carbonate species is thought to be related to this peak [50,[57][58][59][60]. Oxygen species can be divided in to the lattice oxygen (O lattice ) and adsorbed oxygen (O adsorbed ) [57,61]. The area under the XPS peaks can be used to determine the oxygen vacancies on the perovskite lattice, which are typically related to the ratio of O adsorbed to O lattice [62].…”