The sintering behavior of Ca- and Sr-doped lanthanum manganite (the preferred SOFC cathode material) is highly dependent on the relative proportion of A and B site cations in the material. In general, A-site cation deficiency increases sintered density. The effect of additions of YSZ to lanthanum manganite (to ...

The sintering behavior of Ca- and Sr-doped lanthanum manganite (the preferred SOFC cathode material) is highly dependent on the relative proportion of A and B site cations in the material. In general, A-site cation deficiency increases sintered density. The effect of additions of YSZ to lanthanum manganite (to ...

Positional disorder of cations occupying the A sites of C2/m amphiboles has been modeled using structure-energy minimization techniques. Model energy calculations show that, relative to a tremolite end member, local charge deficiency on the T, M4, or O3 sites or charge excess on the M2 sites due to cation substitution will cause ...

New cation-deficient vanadium-iron spinels V{sub 8x/(8+{delta})}Fe{sub (24{minus}8x)/(8+{delta})}{open{underscore}square}{sub 3{delta}/(8+{delta})}O{sub 4} have been obtained by the oxidation at low temperature (<500 C) of the corresponding nanosized stoichiometric spinels V{sub x}Fe{sub 3{minus}x}O{sub 4} octahedral (B) and tetrahedral (A) ...

The crystal structure of new A-site deficient La{sub 5/3}MgTaO{sub 6} perovskite was investigated by neutron, X-ray and electron diffraction. Neutron and X-ray powder diffraction spectra were refined in the monoclinic I2/m space group, with the parameters of the unit cell a=5.6304(2)A, b=5.6226(2)A, c=7.9434(2)A and {beta}=90.04(1){sup o}. This structural ...

The crystal structure of new A-site deficient La5/3MgTaO6 perovskite was investigated by neutron, X-ray and electron diffraction. Neutron and X-ray powder diffraction spectra were refined in the monoclinic I2/m space group, with the parameters of the unit cell a=5.6304(2) �, b=5.6226(2) �, c=7.9434(2) � and ?=90.04(1)�. This structural model ...

The complex perovskite BiMn{sub 7}O{sub 12} occurs with two polymorphic structures, cubic and monoclinic. Currently their crystal structures are investigated with high-resolution synchrotron powder X-ray diffraction at room temperature. Rietveld analysis reveals unusual behavior for, respectively, the oxygen and bismuth atoms in the monoclinic and cubic phases. Bond valence calculations indicate ...

Release of dipicolinic acid (DPA) and its fluorescence with terbium (Tb(3+)) allow rapid measurement of the germination and viability of spores of Bacillus and Clostridium species. However, germination of coat-deficient Bacillus spores was strongly inhibited by Tb(3+) and some other multivalent cations. Tb(3+) also inhibited germination of ...

An investigation has been made on the chemical stability of the cathode-interconnect interface in solid oxide fuel cells. Lanthanum calcium chromite and lanthanum strontium manganite (a dense 10% A-site deficient manganite, a porous 10% A-site deficient one or a dense 1% A-site ...

While most of crystalline wide gap oxides are both stoichiometric and insulating, a handful of them including ZnO and In{sub 2}O{sub 3} are naturally anion-deficient and electron conductors. Even fewer of the oxides are naturally cation-deficient and hole conductors, the arch-type of which is Cu{sub 2}O. Based on first principles calculation of equilibrium ...

... ruled out. Differential phototoxicity with VBBO VBBO, a photosensitive cationic dye that is taken up by mitochondria, ... ...

The synthesis and characterization of the pyrochlore solid solutions, Y{sub 2}Ti{sub 2-x}Nb{sub x}O{sub 7-y}, Lu{sub 2}Ti{sub 2-x}Nb{sub x}O{sub 7-y}, Y{sub 2}Ti{sub 2-x}Ta{sub x}O{sub 7-y} and Lu{sub 2}TiTaO{sub 7-y} (-0.4<y<0.5), is described. Synthesis at 1600 deg. C, and 10{sup -5} Torr yields oxygen deficiency in all systems. All compounds are found to be ...

Magnetite single crystals with Al, Ga and Ti substitutions were measured by means of 57Fe nuclear magnetic resonance (NMR) technique. Satellite structure of NMR spectra well above the Verwey temperature was detected and analyzed to obtain information on the distribution of substituting cations on iron sublattices. It was confirmed that Al and Ti enter iron octahedral B-sites. ...

Co(1-x)M(x)Cr(2)O(4) (M = Li, Zr; x = 0-0.2) catalysts were prepared via the citric acid method and investigated for catalytic combustion of methane. Substitution at tetrahedral (A) sites with monovalent (Li) or tetravalent (Zr) metal ions led to a decrease or increase of the catalytic activity, respectively. The Co(0.95)Zr(0.05)Cr(2)O(4) catalyst proved ...

Aluminum incorporation in the rhombohedrally distorted perovskite lattice of (La0.5Sr0.5)1?xFe1?yAlyO3?? (x=0 0.05, y=0 0.30) decreases the unit cell volume and partial ionic and p-type electronic conductivities, while the oxygen nonstoichiometry and thermal expansion at 900 1200 K increase on doping. The creation of A-site cation vacancies has an opposite effect on the ...

The formation of the DNA G-quadruplex is induced by the addition of a novel porphyrin carrying four cationic tethers. Circular dichroism spectroscopy reveals that the porphyrin binds to Tetrahymena telomeric repeat to form G-quadruplex under stabilizing-cation-deficient and no buffer conditions.

Strontium-doped lanthanum ferrite (LSF) materials have shown considerable promise as solid oxide fuel cell (SOFC) cathodes. When used in conjunction with an anode-supported yttria-stabilized zirconia (YSZ) electrolyte assembly, power densities of 0.7-0.9 W/cm2 at 750 C and 0.7V can be achieved. However, this performance relies on the incorporation of a doped ceria interlayer between the YSZ ...

This paper discusses a method that has been developed to study bulk lattice interdiffusion between calcium and strontium titanate by fabrication of a diffusion couple using cosintering. The measured interdiffusion coefficients, D(C), indicate that strontium impurity diffusion in calcium titanate occurs at a faster rate than calcium impurity diffusion in strontium titanate. These interdiffusion ...

The brownmillerite-type A 2B 2O 5 structure is considered as a parent one, giving rise to different derivatives: layered double perovskites, A-site and anion-vacancy-ordered perovskites, and the perovskite-like compounds with crystallographic shear planes. The structural relationships and synthesis pathways for these classes of materials are discussed with particular attention ...