Olivier Perez

A five-dimensional structural investigation of the misfit layer compound [Bi0.87SrO2]2[CoO2]1.82

The structure of the misfit layer compound [Bi0.87SrO2]2[CoO2]1.82, bismuth strontium cobaltite, was determined by single-crystal X-ray diffraction using the five-dimensional superspace-group formalism. This composite crystal, of monoclinic symmetry, is composed of two subsystems exhibiting incommensurate periodicities along b, the binary axis direction. The first composite part [Bi0.87SrO2] displays an intrinsic modulation of planar monoclinic type characterized by the wavevector q* = 0.293a* + 0.915c*. The second composite part [CoO2] shows two different centered lattice variants. The structure of the misfit layer crystal can be described as an alternation along c of distorted rock-salt-type slabs, formed from [BiO] and [SrO] layers (first subsystem), and of [CoO2] layers (second subsystem) displaying a distorted CdI2-type structure. Two main structural results are obtained. First, as a consequence of the intrinsic modulation, disordered zones, characterized by Bi vacancies, are regularly distributed in the [BiO] layers. Second, strong chemical bonds are implied between the strontium atoms of the first subsystem and the oxygen atoms of the second one.

Thermoelectric Properties of Sintered and Textured Nd-Substituted Ca3Co4O9 Ceramics

We present the results of low- and high-temperature measurements, from 5 to 800 K, of the electrical resistivity and thermoelectric power of polycrystalline and c-axis-oriented textured samples of Ca3-zNdzCo4O9 (0≤z≤0.9). Crystallographic structure, microstructure and texture analyses of the samples have also been carried out. The substitution of the lighter rare-earth large ionic Nd for Ca results in an increase in the Seebeck coefficient. However, the resistivity of the samples also increases accordingly. In addition, the Hall effect of the polycrystalline Ca3-zNdzCo4O9 sample was studied in the 50–300 K interval. This measurement showed that the variation of Seebeck coefficient and resistivity are caused by a decrease in carrier concentration with Nd content. The decomposition temperatures of the samples with Nd content were observed to increase to values beyond the melting point of Ag, the technically important contact material for the fabrication of thermoelectric modules. The studies on the thermoforged samples indicate that the electrical resistivity of the textured samples decreased by 2.5-fold as compared with that of the conventional sintered samples. The increase in the decomposition temperature and the high Seebeck coefficient with low resistivity in thermoforged samples make the Nd-doped Ca3Co4O9 oxide as one of the candidate materials for high-temperature thermoelectric modules.

Structure determination of a brownmillerite Ca 2 Co 2 O 5 thin film by precession electron diffraction

Calcium cobaltite thin films with a nominal ratio

Hydrogen positions in single nanocrystals revealed by electron diffraction.

\text{Ca}/\text{Co}=1

Silver-Based Hybrid Materials from meta- or para-Phosphonobenzoic Acid: Influence of the Topology on Silver Release in Water

were grown on (101)-

Frustration of Magnetic and Ferroelectric Long-Range Order in Bi2Mn4/3Ni2/3O6

{\text{NdGaO}}_{3}

Magnetodielectric coupling and magnetization plateaus in α-CoV2O6 crystals

substrate by the pulsed laser deposition technique. The structure of the as-deposited metastable phase is solved using a precession electron diffraction three-dimensional data set recorded from a cross-sectional sample. We found that an ordered oxygen-deficient

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

{\text{Ca}}_{2}{\text{Co}}_{2}{\text{O}}_{5}

Magnetodielectric Effect in Crystals of the Noncentrosymmetric CaOFeS at Low Temperature

perovskite of the brownmillerite type with lattice parameters

The (3 + 2)D structure of oxygen deficient LaSrCuO3.52

a\ensuremath{\approx}{a}_{p}\sqrt{2}\ensuremath{\approx}5.46\text{ }\text{\AA{}}