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Abstract: The effect of small addition of different sintering aids (MoO3 and WO3) on the electrical properties of Ce0.9Nd0.1O2−δ has been investigated. The (Ce0.9Nd0.1)1−x M x O2−δ (x = 0.0; M = Mo, W, x = 0.01; Ce0.9Nd0.1O2−δ : NDC, (Ce0.9Nd0.1)0.99Mo0.01O2−δ : NDCMo; (Ce0.9Nd0.1)0.99W0.01O2−δ : NDCW) solid solutions were prepared and characterized. The X-ray diffraction patterns indicate that all the samples are single phases with a cubic fluorite structure. Moreover, from the field-emission scanning electron microscopy results, it is found (Ce0.9Nd0.1)0.99M0.01O2−δ (M = Mo, W) sintered at 1300 °C for 15 h have better sinterability than Ce0.9Nd0.1O2−δ . The total conductivity by electrochemical impedance spectroscopy are ranked as: NDCW  > NDCMo  > NDC measured at 700 °C, which is attributed to microstructures. It can be concluded that MoO3 and WO3 are both effective and WO3 seems to be more potential as sintering aids on the optimization of electrical properties for ceria-based electrolytes. [Copyright &y& Elsevier]

A series of novel composite electrolytes based on 20 mol% Gd doped CeO 2 with varying amounts of (Li/Na) 2 SO 4 have been synthesized. X-ray diffraction, thermogravimetry and differential scanning calorimetry, scanning electron microscope and transmission electron microscope were applied to characterize the phase components and microstructures of the composite electrolytes. Their ionic conductivities were determined by AC impedance spectroscopy. It has been found that the optimum sintering temperature and sulphate content for the composite electrolyte is 870 °C and 20 wt% (Li/Na) 2 SO 4 , respectively. Above 550 °C, a sharp increase in conductivity occurred, which can be interpreted as superionic phase transitions in the interface phases between GDC and sulphates. Both the high ionic conductivities above the transition temperature, 0.191, 0.298 and 0.372 S cm −1 at 550, 650 and 750 °C respectively, and low activation energy (0.303 eV) highlight composite GDC-20 wt% (Li/Na) 2 SO 4 a promising electrolyte candidate for application in intermediate temperature solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

The synthesis, crystal structure, and dielectric properties of the titled compounds were described. The structural symmetry was determined to be monoclinic P 2 1 / n (No. 14) space group. Based on the highly ordered array of alternating MgO 6 and SbO 6 octahedra, these double perovskites exhibited significant octahedral tilting distortion according to the Glazer's notation system a − a − c + . As the result of substituting different rare earth ions from La 3+ to Nd 3+ , both the tolerance factor ( t ) and coordination number (CN) were reduced simultaneously and the B-site lattice distorted more heavily with the increase in chemical pressure by adopting smaller Ln 3+ ion. For the investigation of dielectric properties, all the samples consistently presented weak frequency dependent characteristic with relatively low dielectric constant ( ε ') and low tangent loss (tan δ ). With the shrinkage of the Ln 3+ ion size, the corresponding ε ' decreased remarkably and the dispersive tan δ peaks around 300 K shifted to low temperature, indicating that the space-charge-hopping mechanism dominated permittivity property can be tuned by controlling the degree of lattice distortion via substituting different Ln 3+ ions. [ABSTRACT FROM AUTHOR]