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High-performance photovoltaic devices require active photoanodes with superior optoelectric properties. In this study, we synthesized neodymium ruthenate, Nd2Ru2O7 (NRO), and gadolinium ruthenate pyrochlore oxides, Gd2Ru2O7 (GRO), via the solid-state reaction technique, showcasing their potential as promising candidates for photoanode absorbers to enhance the efficiency of dye-sensitized solar cells. A structural analysis revealed predominantly cubic symmetry phases for both materials within the Fd-3m space group, along with residual orthorhombic symmetry phases (Nd3RuO7 and Gd3RuO7, respectively) refined in the Pnma space group. Raman spectroscopy further confirmed these phases, identifying distinct active modes of vibration in the predominant pyrochlore oxides. Additionally, a scanning electron microscopy (SEM) analysis coupled with energy-dispersive X-ray spectroscopy (EDX) elucidated the morphology and chemical composition of the compounds. The average grain size was determined to be approximately 0.5 µm for GRO and 1 µm for NRO. Electrical characterization via I-V measurements revealed that these pyrochlore oxides exhibit n-type semiconductor behavior, with conductivity estimated at 1.5 (Ohm·cm)−1 for GRO and 4.5 (Ohm·cm)−1 for NRO. Collectively, these findings position these metallic oxides as promising absorber materials for solar panels. [ABSTRACT FROM AUTHOR]

The aim of this work was to characterize the natural clinoptilolite from Tasajeras deposit, Cuba, modified by hydrothermal ion-exchange with solutions of iron (II) sulfate and iron (III) nitrate in acid medium. Besides this, its catalytic activity to reduce nitrogen monoxide with carbon monoxide/propene in the presence of oxygen was evaluated. The characterization was performed by Mössbauer and UV-Vis diffuse reflectance spectroscopies and adsorption measurements. The obtained results lead to conclude that in exchanged samples, incorporated divalent and trivalent irons are found in octahedral coordination. Both irons should be mainly in cationic extra-framework positions inside clinoptilolite channels as charge compensating cations, and also as iron oxy-hydroxides resulting from limited hydrolysis of these cations. The iron (III) exchanged samples has a larger amount of iron oxy-hydroxides agglomerates. The iron (II) exchanged samples have additionally iron (II) sulfate adsorbed. The catalytic activity in the nitrogen monoxide reduction is higher in the exchanged zeolites than starting. Among all samples, those exchanged of iron (II) has the higher catalytic activity. This lead to outline that, main catalytically active centers are associated with divalent iron.

A combination of the X-ray diffraction and scanning electron microscopy technique is employed to explain the low temperature synthesis and the magnetic and structural characterization of the manganese sillenite [Bi.sub.12]Mn[O.sub.20] compounds. The relaxation time of the compounds is shown to be completely field dependent.

Extrinsic faulting has been discussed previously within the so-called difference method and random walk calculation. In this contribution it is revisited under the framework of computational mechanics, which allows expressions to be derived for the statistical complexity, entropy density and excess entropy as a function of faulting probability. The approach allows one to compare the disordering process of an extrinsic fault with other faulting types. The ϵ-machine description of the faulting mechanics is presented. Several useful analytical expressions such as probability of consecutive symbols in the Hägg coding are presented, as well as hexagonality. The analytical expression for the pairwise correlation function of the layers is derived and compared with results previously reported. The effect of faulting on the interference function is discussed in relation to the diffraction pattern. [ABSTRACT FROM AUTHOR]

Planar faulting in in rare earth - cobalt alloys with type structures Th2Ni17 and Th2Zn17 are studied. The structure changes from hexagonal for heavy rare earth to rhombohedral for light rare earth, all exhibiting different degrees of planar disorder. Faulting is quantitatively studied beyond the model of independent faulting events showing the strength of direct solutions to extract defects information from the diffraction patterns. It is showed that the analysis of the decaying term of the probability correlation function, does not only allow to quantify the loss of memory in the system through the correlation length but also, the strength of interaction between faults. The behavior of the decaying terms turns not to be of universal character when scaled against the correlation length and instead depends on the interaction of faulting. The reconstructive phase transition in this system seems to follow a path where the new phase appears within the disordered phase and grows without homogeneous reordering of the disordered arrangement. [ABSTRACT FROM AUTHOR]

Abstract: The structural evolution with increasing Nb content in Fe80−x Si20Nb x alloys (0< x ≤12) was investigated by means of high-resolution X-ray diffraction. A metastable NbFe2−x Si x hexagonal phase was found together with cubic bcc Fe100−y Si y solid solution and the amorphous matrix. The grain size of the bcc Fe100−y Si y phase and the strain were determined and their dependencies on the Nb content and heat treatment of the samples were investigated. The strain increases and the grain size decreases with an increasing of Nb content reaching a size down to 37nm. Upon heat treatment of the samples, the hexagonal phase decomposes in two hexagonal phases with similar compositions. [Copyright &y& Elsevier]

Abstract: Investigations of the magnetic properties of NbFe2 were performed by measuring the temperature dependence of hysteresis loops, initial AC-susceptibility and zero field cooled (ZFC)–FC magnetizations in a wide field range of 50Oe⩽μ 0 H⩽8000Oe. Two well-defined peaks, at 4.8 and 21.4K, were found in the AC-susceptibility curve, and only the first peak is sensible to a frequency change of the applied field. The peak changes to high temperature and its intensity decreases with increasing frequency, thus showing a relaxation phenomenon. In ZFC magnetization at 50Oe, the peaks occur at 3.4 and 21.4K. With increasing DC field, both peaks are shifted to low temperatures; however, the first peak disappears at fields higher than 100Oe and a field higher than 1250Oe suppresses the second peak. A third maximum merges from the magnetization curve at around 7K in a field of 500Oe, in which case, the maximum is suppressed by an external field higher than 4000Oe. One can suggest that the ordered state of the stoichiometric NbFe2 is a spin density wave (SDW) and both ferro- and antiferromagnetic spin fluctuations coexist. [Copyright &y& Elsevier]

Extrinsic faulting has been discussed previously within the so-called difference method and random walk calculation. In this contribution it is revisited under the framework of computational mechanics, which allows expressions to be derived for the statistical complexity, entropy density and excess entropy as a function of faulting probability. The approach allows one to compare the disordering process of an extrinsic fault with other faulting types. The ℇ-machine description of the faulting mechanics is presented. Several useful analytical expressions such as probability of consecutive symbols in the Hägg coding are presented, as well as hexagonality. The analytical expression for the pairwise correlation function of the layers is derived and compared with results previously reported. The effect of faulting on the interference function is discussed in relation to the diffraction pattern.