Shengli Pang

Evaluation of Ba-deficient PrBa1−xFe2O5+δ oxides as cathode materials for intermediate-temperature solid oxide fuel cells

Cobalt-free double perovskite oxides are promising cathode materials in intermediate-temperature solid oxide fuel cells, and often suffer from low activity in oxygen reduction reactions. Here, we report on Ba deficiency as an effective strategy to enhance the electrochemical performance of cobalt-free double perovskite PrBaFe2O5+δ, which is related to the formation and redistribution of oxygen vacancies in double perovskite. The effect of Ba deficiency on crystal structure, surface properties, oxygen content, electrical conductivity, thermal expansion, chemical compatibility with gadolinium-doped ceria (Gd0.1Ce0.9O1.95) electrolyte, microstructure, and electrochemical performance of PrBa1−xFe2O5+δ (x = 0.00–0.03) was evaluated systematically. Our preliminary results suggest that Ba deficiency is a feasible means to tailor the physico- and electrochemical properties of cobalt-free double perovskite, and that PrBa0.97Fe2O5+δ is a potential cathode material for intermediate-temperature solid oxide fuel cells.

Oxygen Vacancy Dynamics at Room Temperature in Oxide Heterostructures

Oxygen vacancy dynamic behavior at room temperature in complex oxides was carefully explored by using a combined approach of ion liquid gating technique and resistance measurements. Heterostructures of PrBaCo2O5+δ/Gd2O3-doped CeO2 epitaxial thin films were fabricated on (001) Y2O3-stabilized ZrO2 single crystal substrates for systematically investigating the oxygen redox dynamics. The oxygen dynamic changes as response to the gating voltage and duration were precisely detected by in situ resistance measurements. A reversible and nonvolatile resistive switching dynamics was detected at room temperature under the gating voltage >13.5 V with pulse duration >1 s.

Ca doping effect on the magnetic and electronic transport properties in double perovskite PrBaCo2O5+δ films

Ca doped double perovskite PrBa1-xCaxCo2O5+δ (x = 0, 0.3, and 0.5) thin films were epitaxially grown on the (001) SrTiO3 substrates to systematically investigate the A′ site doping effect on the magnetic and electronic transport properties. With the increase in the Ca content, the magnetization measurements on the films show that the magnetic moments are significantly increased and the largest magnetic moment of 88 emu/cm3 can be achieved in the film with x = 0.5 or about 90 times larger than that from the undoped PrBaCo2O5+δ film. The electronic transport property measurements on the films indicate that the electrical conductivity can be altered by various Ca doping contents. It is interesting to note that both undoped PrBaCo2O5+δ and PrBa0.5Ca0.5Co2O5+δ films exhibit simple activation behavior, but the PrBa0.7Ca0.3Co2O5+δ film exhibits the 3D variable-range hopping mode conduction.