The misfit compound [CoO2][Ca2CoO3−δ]0.62 is well-known for its good potentialities in the field of thermoelectric oxides combining good electronic transport, high Seebeck coefficient, and low thermal conductivity. Its 2D-crystal structure can be regarded as a natural intergrowth between electronic-conducting Co3+/Co4+ hexagonal layers and oxygen deficient Co2+/Co3+ rock-salt layers with low thermal conductivity. Their lacunar character suggests a possible anionic conductivity. We took advantage of this model for application as a SOFC cathode material. Additional advantages appear from the good chemical and mechanical adaptability (TEC = 9−10 × 10−6 °C−1) with intermediate temperature electrolyte, namely, CGO. The manufactured symmetrical cells show a good electrode/electrolyte adherence, stable after long-time experiments. Our promising preliminary electrochemical tests show a rather low electrode overpotential (4Ω·cm2) for ∼40 μm thick layers with a rather dense microstucture. The porosity and electric performances are improved in the composite with 30 wt % CGO (∼1 Ω·cm2). In general, from polarization experiments versus temperature and oxygen pressure, we found two distinct processes, frequency-separated, that is, HF, charge transfer at the TPB with intrinsic O2− diffusion; LF, gas transfer/oxygen dissociation. This latter is largely fastened in the CGO/Ca3Co4O9−δ, reminiscent of the existing but limiting ionic mobility in the single phase of the title compound.

In order to find out more about the suppression of ferromagnetic (FM) interactions in Sr1-xLaxRuO3, electronic structures and magnetic properties have been investigated upon changing x from 0.0 to 0.5, using an XRD method with Rietveld analysis, a SQUID magnetometer and a DV-Xα computational method. In comparison with magnetic properties in Sr1-xCaxRuO3, FM interactions in Sr1-xLaxRuO3 are found to be suppressed very rapidly against x. Neither structural distortion nor cation-size disorder can account for such rapid suppression. Instead, this may be attributed to the effect of La-O hybridization created by La substitution for Sr. This hybridization effect weakens the FM order around Ru ions and, as a result, the long-range FM states are suppressed even if x is small. The DV-Xα cluster method was employed to estimate the energy difference between the up and down spin density of states in SrRuO3 and Sr0.5La0.5RuO3. This calculation predicts that Sr1-xLaxRuO3 contains La-O hybridization which suppresses FM interaction even at small x.

Low temperature dielectric properties of YMn 0.95 Ru 0.05 O 3 AIP Conf. Correlation between high ionic conductivity and twin structure of La 0.95 Sr 0.05 Ga 0.9 Mg 0.1 O 3 − δ Nature of small-polaron hopping conduction and the effect of Cr doping on the transport properties of rare-earth manganite La 0.5 Pb 0.5 Mn 1−x Cr x O 3In order to identify the carrier responsible for the electrical transport at room temperature in LiMn 2 O 4 from the viewpoint of practical applications as a cathode material, the bulk conductivity measurements by complex-plane impedance analyses have been carried out on LiMn 2 O 4 , Li 0.95 Mn 2 O 4 , and LiMn 1.95 B 0.05 O 4 ͑BϭAl 3ϩ or Ga 3ϩ ͒ together with the measurements of four-probe dc conductivities and dielectric relaxation processes, because these are two candidates for the carrier, a Li ion or a nonadiabatic small polaron of an e g electron on Mn 3ϩ . The comparison of the ionic conductivity estimated numerically from the parameters obtained experimentally for the Li-diffusion in LiMn 2 O 4 with the bulk conductivity indicates that the Li-diffusion seems difficult to play the primary role in the electrical conduction. Instead, a hopping-process of nonadiabatic small polarons of e g electrons is likely to dominate predominantly the electrical transport properties. The dielectric relaxation process, and the activation energies and the pre-exponential factors of the bulk conductivities in Li 0.95 Mn 2 O 4 and LiMn 1.95 B 0.05 O 4 are explained self-consistently in terms of the polaronic conduction.

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