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Microstructural stability is a crucial but controversial issue for Mg-Al-RE alloys. It is important to study the thermal stability of Al-RE intermetallic phase with individual RE element. In this work, Mg-4Al-4Nd-0.2Mn (AlNd44, wt%) alloy with individual RE element Nd was prepared by high-pressure die-casting (HPDC). The microstructure, microstructural stability and its effects on tensile properties and corrosion behavior were investigated. The results show that the HPDC AlNd44 alloy has two intermetallic phases, i.e., acicular Al 11 Nd 3 and particulate Al 2 Nd, which are distributed at grain/dendritic boundary regions and form reticular structure. According to the quantitative X-ray diffraction phase analysis, the content of Al 11 Nd 3 and Al 2 Nd phases is 2.5 wt% and 1.8 wt%, respectively. Both the two phases appear to be thermally stable at 473 K. While the acicular Al 11 Nd 3 phase has a tendency to decompose at temperature up to 573 K, and would decompose to particulate Al 2 Nd phase thoroughly at 673 K. Moreover, Al 2 Nd phase would also partly decompose at temperature above 573 K. The alloy in as-cast state, with an intermetallic skeleton at grain/dendritic boundary regions, exhibits relatively high tensile properties and corrosion resistance. In contrast, the alloy after annealing at 673 K has the worst tensile properties and corrosion resistance due to the obvious phase transition and microstructure change.

A series of perovskite oxides SrBiMTiO6 (M = Fe, Mn, Cr) have been synthesized and characterized towards application as cathode materials for solid oxide fuel cells (SOFCs). X-ray diffraction (XRD) patterns reveal that all samples are stabilized in $$ \mathrm{Pm}\ \overline{3}\mathrm{m} $$ space group. Electrical conductivity, AC impedance characteristics, and thermal and chemical stability have been studied in order to assess their possible use as SOFC cathode materials. In comparison with other low electrical conductivity cathodes of SOFC, our results suggest that SrBiMnTiO6, which has the highest electrical conductivity (4.02 S cm−1) and moderate polarization resistance (0.104 Ω cm2) at 850 °C, is the most promising candidate among the three perovskite oxides for further study and optimization as a SOFC cathode material.

The B-site ordered double perovskite oxides LaPbMSbO6 (M=Co, Ni) have been synthesized via the modified Sol–Gel precursor two-step route. Rietveld refinements reveal strong abnormal structural distortion and BO6 octahedral deformation appearing along the ab plane. Owing to the cooperative Jahn–Teller effect of Co2+ and Pb2+ ions, the Co-related compound exhibits almost complete Co2+–Sb5+ order. For magnetic properties, spin-canted antiferromagnetic state with high extent of magnetic frustration is confirmed. The Ni-related compound presents heavier magnetic frustration for introducing tiny disorder on site occupation accompanied with valence state and further enhancing the complexity of magnetic competition. Dielectric measurements present a considerable temperature dependent dielectric relaxation with great dc-like loss feature in the LaPbCoSbO6. For LaPbNiSbO6, however, the permittivity with low dielectric loss is shown to be insensitive to either temperature or frequency. The corresponding electronic active energy manifests that the weakly bounded 3d-electron is prone to hop in a more distorted Co–Sb sublattice.

To date great efforts have been devoted to the development of solid oxide fuel cell (SOFC) devices that is able to run at intermediate temperature (IT) and to retain good electrochemical performance as in the high temperature regime. To this end, Tantalum (Ta) is doped into Sr 2 Fe 1.5 Mo 0.5− x Ta x O 6− δ (0.0 ≤ x ≤ 0.15) to further improve the electrochemical performance as the cathode materials for IT-SOFC. Pure orthorhombic Sr 2 Fe 1.5 Mo 0.5− x Ta x O 6− δ (0.0 ≤ x ≤ 0.15) samples, with space group Pnma (no. 62), are synthesized by a two-step method and identified via the powder X-ray Rietveld refinements. X-ray photoelectron spectroscopy and thermogravimetry results consistently show that the number of oxygen vacancy increases with the increasing of Ta content. The thermal expansion compatibility of the samples is found to match the electrolyte of La 0.9 Sr 0.4 Ga 0.1 Mg 0.2 O 3− δ (LSGM) better than that of cobalt-containing electrode compounds. Finally, the higher oxygen vacancy concentration leads to the enhanced ionic conductivity although electrical conductivity is slightly decreased due to the oxygen vacancy blocking. Therefore, Ta-doped Sr 2 Fe 1.5 Mo 0.5 O 6− δ is proved to be a promising candidate for future cathode materials of IT-SOFC.

The crystal structures, magnetic and dielectric properties for the ordered double perovskites LnPbNiSbO6 (Ln = La, Pr) have been investigated. Rietveld refinements of x-ray diffraction data have been indexed for the monoclinic symmetry in space group P21/n (No. 14) and a highly rock-salt ordered arrangement of NiO6 and SbO6 octahedra. The B-site lattices are distorted strongly due to the substitution of rare Earth ions at the A-site. The magnetization measurements show an antiferromagnetic ordering. The effective magnetic moments μ eff are larger than the spin-only values, suggesting that the orbital component for Ni2+ is significant. The maximum values of isothermal magnetization increase due to the lattice distortion of BO6 octahedra, which may weaken the antiferromagnetic interaction via Ni2+–O–Sb5+–O–Ni2+ paths. The dielectric constants for LaPbNiSbO6 present frequency dependence and the tan δ curves exhibit relaxor-like dielectric response. The e' decreases with the reduction of the magnetic moments of B-site transition metal ions, which reveals a relationship between the dielectric and magnetic properties.

Single-component electrolyte-free fuel cells possess a similar function to the traditional fuel cells with a complex three-component structure. However, how to enhance their electrical properties for practical industrial applications remains a timely and important issue. Here, we report the manipulation of concentration ratios of ionic to electronic conductors in an electrolyte-free Ce0.8Sm0.2O2-δ–Li0.15Ni0.45Zn0.4 by adjusting the relative weight between its two inside compositions. Our systematic investigations reveal that the fuel cell with 30% in weight of Li0.15Ni0.45Zn0.4 exhibits an almost uniform distribution of the two compositions and has a total conductivity as high as 10 × 10−2 S cm−1 at 600 °C. Such an enhancement is found to be attributed to the established balance between the numbers of its inside ionic and electronic conductors. These findings are relevant for the technological improvement of this new species of electrolyte-free fuel cell and represent an important step toward commercialization of this single-component fuel cell.