Development of chemically stable proton conductors for solid oxide fuel cells (SOFCs) will solve several issues, including cost associated with expensive inter-connectors, and long-term durability. Best known Y-doped BaCeO3 (YBC) proton conductors-based SOFCs suffer from chemical stability under SOFC by-products including CO2 and H2O. Here, for the first time, we report novel perovskite-type Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3−δ by substituting Sr for Ba and co-substituting Gd + Zr for Ce in YBC that showed excellent chemical stability under SOFC by-products (e.g., CO2 and H2O) and retained a high proton conductivity, key properties which were lacking since the discovery of YBCs. In situ and ex- situ powder X-ray diffraction and thermo-gravimetric analysis demonstrate superior structural stability of investigated perovskite under SOFC by-products. The electrical measurements reveal pure proton conductivity, as confirmed by an open circuit potential of 1.15 V for H2-air cell at 700°C, and merits as electrolyte for H-SOFCs.

In this tutorial review, we discuss the defect chemistry of selected amphoteric oxide semiconductors in conjunction with their significant impact on the development of renewable and sustainable solid state energy conversion devices. The effect of electronic defect disorders in semiconductors appears to control the overall performance of several solid-state ionic devices that include oxide ion conducting solid oxide fuel cells (O-SOFCs), proton conducting solid oxide fuel cells (H-SOFCs), batteries, solar cells, and chemical (gas) sensors. Thus, the present study aims to assess the advances made in typical n- and p-type metal oxide semiconductors with respect to their use in ionic devices. The present paper briefly outlines the key challenges in the development of n- and p-type materials for various applications and also tries to present the state-of-the-art of defect disorders in technologically related semiconductors such as TiO(2), and perovskite-like and fluorite-type structure metal oxides.

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As a highly efficient-clean power generation technology, intermediate temperature (600-800 °C) solid oxide fuel cells (IT-SOFCs) have gained much interest due to their rapid start-up and shut-down capability, longer life-time...

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In this work, synthesis and characterization of an anode supported tubular solid oxide fuel cell based on Ba 0.5 Sr 0.5 Ce 0.6 Zr 0.2 Gd 0.1 Y 0.1 O 3-δ (BSCZGY) electrolyte has been investigated. Anode-supported Ni -yttria-stabilized zirconia (YSZ) anode was fabricated via slip casting; BSCZGY electrolyte and BSCZGY -La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) composite cathode were coated on support using dip coating, respectively. The chemical compatibility of fuel cell components at sintering temperatures has been investigated by powder X-ray diffraction, and no severe reactions were detected. Electrochemical examination under air/H 2 + 3 vol. % H 2 O showed superior performance achieving a maximum power density of 1 W/cm 2 at 850 • C, among the best compared to tubular -geometry oxygen conductor solid oxide fuel cells reported earlier and one of the highest reported for a proton conductor electrolyte in literature. Electrochemical impedance spectroscopy was used to examine the electrochemical performance of the full cell at different temperatures, and a detailed analysis was done to distinguish the contribution of ohmic and polarization resistances of the cell. ASR values were 3.47 .cm 2 , 1.81 .cm 2 , 1.23 .cm 2 , and 1.05 .cm 2 at 600, 700, 800, and 850 • C, respectively. Analysis of activation energy associated with charge and mass transfer based on fitting of impedances revealed that concentration polarization is the major contributor to the total resistance. The long-term stability for more than 96 hours of operation under load showed no significant degradation, which demonstrated the steady behavior of the cell. A solid oxide fuel cell (SOFC) is a solid-state electrochemical device which converts the chemical energy stored in the fuel directly into electrical energy resulting in high efficiency which along with low environmental impact, quiet operation, and low maintenance makes SOFC highly suitable for stationary power generation applications. 1Traditional SOFCs employ Ni-YSZ cermet, oxide-ion conducting yttria-stabilized zirconia (YSZ), and lanthanum strontium manganite as the anode, electrolyte and cathode, respectively.2 To reduce the overpotentials associated with these materials, the cell needs to run at elevated temperatures near 1000• C. 3 This negatively affects the choice of available materials mostly for interconnects and sealants and their long-term stability. 4 To reduce the operating temperature of SOFC, one of the alternative is to develop new materials for cell components. Oxide ion conducting electrolytes La 0.9 Sr 0.1 Ga 0.

Perovskite-type metal oxides are being used in a wide range of technologies, including fuel cells, batteries, electrolyzers, dielectric capacitors, and sensors. One of their remarkable structural properties is cationic ordering in A or B sites, which affects electrical transport properties under different gaseous atmospheres, and chemical stability under CO and humid conditions. For example, a simple-perovskite-type Y-doped BaCeO forms BaCO and ((Ce,Y)O) under CO at elevated temperature, while B-site-ordered double-perovskite-type BaCaNbO remains chemically stable under the same conditions. Early structural studies on BaCaNbO (BCN) showed that the B-site ordering (1:1) is sensitive to the Ca content. However, ambiguity rises, as 1:2 B-site ordering was not observed in the parent and doped analogues when x was varied, which motivated us to revisit the complex oxides BCN ( x = 0-0.45) to determine the atomic structure by a mean of combined synchrotron X-ray and neutron diffraction methods. Surprisingly, the B-site ordering increases with increasing Ca/Nb mixing in the B-sites in BCN. In addition, the electrical conductivity of BCN was found to be the highest at x = ∼0.18, and it decreased as the Ca/Nb ratio further increased in BCN. Such a result was very similar to that for the Y-doped BaZrO, where the mobility of proton carriers was found to decrease as the dopant (Y) increased. A higher Ca/Nb ratio also promotes the growth of grain size, as Ca ions could serve as a sintering aid, improving the structural integrity.

Solid oxide fuel cells (SOFCs) are solid-state electrochemical devices that directly convert chemical energy of fuels into electricity with high efficiency. Because of their fuel flexibility, low emissions, high conversion efficiency, no moving parts, and quiet operation, they are considered as a promising energy conversion technology for low carbon future needs. Solid-state oxide and proton conducting electrolytes play a crucial role in improving the performance and market acceptability of SOFCs. Defect fluorite phases are some of the most promising fast oxide ion conductors for use as electrolytes in SOFCs. We report the synthesis, structure, phase diagram, and high-temperature reactivity of the ScV O (0 ≤ x ≤ 2.00) oxide defect model system. For all ScV O phases with x ≤ 1.08 phase-pure bixbyite-type structures are found, whereas for x ≥ 1.68 phase-pure corundum structures are reported, with a miscibility gap found for 1.08 < x < 1.68. Structural details obtained from the simultaneous Rietveld refinements using powder neutron and X-ray diffraction data are reported for the bixbyite phases, demonstrating a slight V preference toward the 8b site. In situ X-ray diffraction experiments were used to explore the oxidation of the ScV O phases. In all cases ScVO was found as a final product, accompanied by ScO for x < 1.0 and VO when x > 1.0; however, the oxidative pathway varied greatly throughout the series. Comments are made on different synthesis strategies, including the effect on crystallinity, reaction times, rate-limiting steps, and reaction pathways. This work provides insight into the mechanisms of solid-state reactions and strategic guidelines for targeted materials synthesis.