Volume 91, Issue 6

Relationships between the various physical and chemical properties of isostructural compounds take place according to the Periodic Table that is a fundamental basis of Chemistry. The systematization of this approach, data vs. the Periodic Table, will contribute to further development of the solid state chemistry theory. The lanthanides and the actinides make up the f block of the Periodic Table. The lanthanides are the elements produced as the 4 f sublevel is filled with electrons and the actinides are formed while filling the 5 f sublevel. In this paper, we analyze some classes of compounds formed by the lanthanides with other elements of the Periodic Table, which can count into the thousands of binary compounds. The special place of lanthanides in the Periodic System of Elements made it possible to establish strict nonlinear relationships between the standard entropy and the lanthanide atomic number of the compounds Ln 2 X 3 ( X  = O, S, Se, Te), Ln N, Ln B 4 , and Ln F 3 in the solid state. This relationship, based on tetrad-effect, can be applied to other physical and chemical properties of the isostructural compounds. The thermodynamic properties of actinides have been studied much less than lanthanides, but the similarity of physicochemical properties makes it possible for us to estimate, with sufficient accuracy, unexplored properties using fundamental laws. One of these laws is the tetrad-effect concept that is an effective tool to predict missing thermodynamic values for lanthanide and actinide compounds and to rationally plan experiments.

In this work results of studies on the short-range order and on the atomic dynamics in different stable and undercooled glass-forming metallic melts are reviewed. In order to undercool the melts deeply below the melting temperature and to avoid chemical reactions of the melts with crucible materials, the samples are containerlessly processed utilizing the electromagnetic or the electrostatic levitation technique. The short-range structure of the melts is studied by neutron diffraction, while the atomic dynamics are investigated by quasielastic neutron scattering. The relationship between short-range structure and atomic dynamics is discussed within the mode coupling theory of the glass transition. We will show that taking the time- and space-averaged structural information provided by measured partial structure factors as an input, mode coupling theory is able to explain the experimental results concerning the activation energies for self-diffusion and the coupling/decoupling behavior of the self-diffusion coefficients of the different alloy components.

This work combines new and earlier obtained results on electron hole and oxygen-ion transport in the La 2 NiO 4 -based solid solutions. The effect of lanthanum substitution with Ca/Sr and nickel with Fe, Mn, Co or Cu on transport properties of La 2− x A x Ni 1− y Me y O 4+δ was analyzed and discussed at different substitution levels. Besides the changes in concentration and mobility of electron holes induced by the doping with cations of different nature, the partial transformation of Ni 3+ from low-spin to high-spin state was shown to have a profound effect on transport properties of these materials leading to a notable decrease in mobility of electron holes, especially in the strontium-rich oxides. The obtained results suggested that the size factor was the main driving force behind the observed transformation of Ni 3+ . The oxygen-ion transport in La 2− x A x Ni 1− y Me y O 4+δ was characterized by significant surface exchange limitations, which can be reduced only at relatively high concentrations of strontium and iron, and should be taken into account while evaluating the ionic conductivity by means of oxygen permeation or the modified Hebb-Wagner polarization method.

This work, based on the experimental and theoretical research carried out by the authors during the last decade, presents an overview of formation, stability and defect thermodynamics, crystal structure, oxygen nonstoichiometry, chemical strain and transport properties of the double perovskites REBaCo 2−x M x O 6−δ (RE = La, Pr, Nd, Eu, Gd, Y; M = Fe, Mn). These mixed-conducting oxides are widely regarded as promising materials for various energy conversion and storage devices. Attention is focused on (i) thermodynamics of formation and disordering, oxygen nonstoichiometry, crystal and defect structure of the double perovskites REBaCo 2−x M x O 6−δ , as well as their thermodynamic stability and the homogeneity ranges of solid solutions, (ii) their overall conductivity and Seebeck coefficient as functions of temperature and oxygen partial pressure and (iii) the anisotropic chemical strain of their crystal lattice. The relationships between the peculiarities of the defect structure and related properties of the double perovskites are analysed.

The search and exploration of new materials not found in nature is one of modern trends in pure and applied chemistry. In the present work, we report on experimental and ab initio density-functional study of the high-pressure-synthesized series of compounds Mn 1− x (Co,Rh) x Ge. These high-pressure phases remain metastable at normal conditions, therewith they preserve their inherent noncentrosymmetric B20-type structure and chiral magnetism. Of particular interest in these two isovalent systems is the comparative analysis of the effect of 3 d (Co) and 4 d (Rh) substitution for Mn, since the 3 d orbitals are characterized by higher localization and electron interaction than the 4 d orbitals. The behavior of Mn 1− x (Co,Rh) x Ge systems is traced as the concentration changes in the range 0 ≤  x  ≤ 1. We applied a sensitive experimental and theoretical technique which allowed to refine the shape of the temperature dependencies of magnetic susceptibility χ ( T ) and thereby provide a new and detailed magnetic phase diagram of Mn 1− x Co x Ge. It is shown that both systems exhibit a helical magnetic ordering that very strongly depends on the composition x . However, the phase diagram of Mn 1− x Co x Ge differs from that of Mn 1− x Rh x Ge in that it is characterized by coexistence of two helices in particular regions of concentrations and temperatures.

In this study, rice husk ash (RHA) silanized with 3-glycidyloxypropyl trimethoxysilane was used as support material to immobilize Candida antarctica lipase B. The developed biocatalyst was then utilized in the ring opening polymerization (ROP) of ε-caprolactone and in situ development of PCL/Silica nanohybrid. The silanization degree of RHA was determined as 4 % (w) by thermal gravimetric analysis (TGA). Structural investigations and calculation of molecular weights of nanohybrids were realized by proton nuclear magnetic resonance ( 1 H NMR). Crystallinity was determined by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Scanning Electron Microscopy (SEM) was used for morphological observations. Accordingly, the PCL composition in the nanohybrid was determined as 4 %, approximately. Short chained amorphous PCL was synthesized with a number average molecular weight of 4400 g/mol and crystallinity degree of 23 %. In regards to these properties, synthesized PCL/RHA composite can find use biomedical applications.

PP-based composites with two mineral fillers (perlite or glass beads) were manufactured by extrusion, and then subjected to orientation in a ratio of 3:1. Electrets were obtained in the polarization process under the influence of a constant electric field. Sample morphology was tested by SEM whereas the crystallinity was determined by XRD. Mechanical strength and thermal stability of composites was studied by tensile tests and thermogravimetric analysis, respectively. The piezoelectric characteristics were appointed by measurement of the electrical charge and current voltage in the polarized samples. The dependence of thermally stimulated depolarized current (TSDC) on temperature was also investigated. The piezoelectric coefficient (d 33 ), the electret stability over time as well as activation energy of depolarization process have been determined. It was found that low filler content (i.e. 2.5 and 5 wt.% of glass beads and perlite, respectively) significantly improve piezoelectric properties of isotactic polypropylene (i-PP).

Polyelectrolytes (PEs) bearing easily derivatizable functions for possible post-modification under mild conditions can find a broad range of applications in various fields. The present paper describes the successful controlled side-chain allylation of two types of PEs: polyamine-based polycations, i.e. poly(allylamine hydrochloride) (PAH) and branched polyethyleneimine (PEI), and strong polyanions, i.e. poly(sodium vinyl sulfonate) (PVS) and poly(sodium 4-styrene sulfonate) (PSS). PSS has been largely investigated in the literature, while PVS is much less commonly explored. The allylation of each type presents its own drawback, i.e. heterogeneous reaction in the case of strong polyanions and instability of partially protonated allylated polyamine products. Nevertheless, all encountered difficulties could be solved and thoroughly elucidated by different experimental tests. This partial allyl-functionalization does not affect the electrolytic properties of the newly allylated PEs, as evidenced by the effective construction of two series of polyelectrolyte multilayer (PEM) films, namely PEI-ene (PSS-ene/PAH-ene) 4 and PEI-ene (PVS-ene/PAH-ene) 4 , the latter being one of the rare examples developed in the literature. The presence of allyl groups on the PE side-chains allows for the stabilization of the resulting PEM films via thiol-ene photo-crosslinking in the presence of a water-soluble dithiol crosslinker. In order to fix permanently the resulting crosslinked PEM films on substrates, the covalent crosslinking occurs not only between different C=C bonds on PE layers but also with those present on substrates preliminarily functionalized with allyl groups via sulfur–gold chemistry. The robustness of both resulting crosslinked PEM films under strongly basic solution (pH 14) is validated by Quartz Crystal Microbalance (QCM) measurements. The versatility and effectiveness of the present approach is expected to find potential applications in different scientific and technological fields.

This paper provides a list of the most important terms from all areas of polymer science including polymer chemistry, polymer physics, polymer technology and polymer properties. These have been assembled into a representative list of terms that serves as an IUPAC recommended list of keywords for polymer science.

Trace elements analysis is a fundamental challenge in environmental sciences. Scientists measure trace elements in environmental media in order to assess the quality and safety of ecosystems and to quantify the burden of anthropogenic pollution. Among the available analytical techniques, X-ray based methods are particularly powerful, as they can quantify trace elements in situ . Chemical extraction is not required, as is the case for many other analytical techniques. In the last few years, the potential for X-ray techniques to be applied in the environmental sciences has dramatically increased due to developments in laboratory instruments and synchrotron radiation facilities with improved sensitivity and spatial resolution. In this report, we summarize the principles of the X-ray based analytical techniques most frequently employed to study trace elements in environmental samples. We report on the most recent developments in laboratory and synchrotron techniques, as well as advances in instrumentation, with a special attention on X-ray sources, detectors, and optics. Lastly, we inform readers on recent applications of X-ray based analysis to different environmental matrices, such as soil, sediments, waters, wastes, living organisms, geological samples, and atmospheric particulate, and we report examples of sample preparation.