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Bulk SrFe12O19/(Ni0.4Zn0.6)Fe2O4 composite ferrites with mass ratios R m = 2 : 1, 1 : 1 and 1 : 2 were prepared using nanopowders obtained via a hydrothermal method, and their phase composition, magnetic properties, exchange coupling (EC) and magnetic microstructures were systematically investigated. It is found that all the bulk specimens sintered at either 700 or 900 °C are composed of two phases but exhibit typical single-phase magnetic behaviours, indicating the existence of EC between the magnetically hard and soft phases. However, too much (R m = 2 : 1) or too little (R m = 1 : 2) soft (Ni0.4Zn0.6)Fe2O4 phase weakens the EC in the composites. It is also proved that except for the EC, the strengthening of chemical polarization of the internal chemical bonds affects saturation magnetization, and the size of nanoscale grains significantly influences the EC and magnetic properties. In addition, novel stripe domains are found in all of the bulk composite specimens, which could be ascribed to the magnetization of the soft (Ni,Zn)Fe2O4 phase induced by the hard SrFe12O19 phase.

The spinel ZnFe 2 O 4 specimens were obtained via a hydrothermal and a ceramic method, respectively, and their structural and magnetic properties were comparatively studied. It was found that all the specimens exhibited a single-phase and mixed spinel structure. The magnetism of specimens synthesized via the hydrothermal method is obviously greater than that of specimen prepared via the ceramic method. This can be ascribed to the occupancy of Fe ions resulted from the loss of Zn during the hydrothermal process.

Metal ion diffusion is an effective strategy to suppress the internal electronic short circuit in ceria‐based solid oxide fuel cells (SOFCs). This could be achieved by fabricating an electron‐blocking layer between the barium‐containing anode and ceria‐based electrolyte. In this paper, a 0.6NiO‐0.4BaZr0.1Ce0.7Y0.2O3‐δ (NiO‐BZCY) anode‐supported cell based on Gd0.1Ce0.9O2‐δ (GDC) electrolyte was employed to evaluate the internal metal ion diffusion behavior. The high open circuit voltages of about 1 V obtained at 550‐700°C can be attributed to in situ formation of an electron‐blocking interlayer between NiO‐BZCY and GDC. Microstructural analyses of the interlayer grains obtained by traditional solid‐state reaction were carried out. Phase identification demonstrated that the electron‐blocking interlayer had a perovskite structure. SEM and TEM analyses indicated formation of a new compound in the interlayer, of which the composition was determined as Zr, Y, and Ni co‐doped BaCe0.9Gd0.1O3 with orthorhombic structure.

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