6 research outputs found
Nonstoichiometry, Defect Chemistry and Oxygen Transport in Fe-Doped Layered Double Perovskite Cobaltite PrBaCo2−xFexO6−δ (x = 0–0.6) Membrane Materials
Mixed conducting cobaltites PrBaCo2−xFexO6−δ (x = 0–0.6) with a double perovskite structure are promising materials for ceramic semi-permeable membranes for oxygen separation and purification due to their fast oxygen exchange and diffusion capability. Here, we report the results of the detailed study of an interplay between the defect chemistry, oxygen nonstoichiometry and oxygen transport in these materials as a function of iron doping. We show that doping leads to a systematic variation of both the thermodynamics of defect formation reactions and oxygen transport properties. Thus, iron doping can be used to optimize the performance of mixed conducting oxygen-permeable double perovskite membrane materials
Synthesis and Properties of Rubidium Salts of Phosphotungstic Acid
The work is devoted to the study of the influence of synthesis conditions on the properties of water-insoluble rubidium salts of phosphotungstic acid (PTA). Such heteropoly compounds have a wide range of applications, including in the field of electrocatalysts and solid electrolytes for various electrochemical devices. The acid salts of PTA with high activity of acid sites on the particle surface are of particular interest. It is known that the properties of water-insoluble PTA salts strongly depend on synthesis conditions, such as the ratio of reagents, temperature, concentrations, and other parameters. The work examines the influence of the ratio and concentration of reagents on the sizes of crystallites and agglomerates, specific surface area (SSA), porosity, water content, and ionic conductivity of the synthesized PTA salts. The SSA value of the obtained samples varied in the range of 84–123 m2 g−1, and the ionic conductivity was 13–90 mS cm−1 at room temperature and 75% RH. An increase in the acid concentration and the degree of proton substitution led to an increase in SSA, accompanied by an increase in particle sizes without changing the size of crystallites. The results of the work may be useful for the development of new materials based on the obtained salts in many fields, including hydrogen energy
RIDME Spectroscopy with Gd(III) Centers
The
relaxation induced dipolar modulation enhancement (RIDME) technique
is applied at W-band microwave frequencies around 94 GHz to a pair
of Gd(III) complexes that are connected by a rodlike spacer, and the
extraction of the interspin distance distribution is discussed. A
dipolar pattern derived from RIDME experimental data is a superposition
of Pake-like dipolar patterns corresponding to the fundamental dipolar
interaction and higher harmonics thereof. Intriguingly, the relative
weights of the stretched patterns do not depend significantly on mixing
time. As much larger modulation depths can be achieved than in double
electron–electron resonance distance measurements at the same
frequency, Gd(III)–Gd(III) RIDME may become attractive for
structural characterization of biomacromolecules and biomolecular
complexes