The combination of the unique, abnormal properties shown by oxidic systems with structure of spinel on the basis of transitional elements chromites draws attention of researchers for many years. Some systems on the basis of transitional elements chromites (for example, nickel and copper chromites) have critical elements (multicritical points, lines of phase transitions of the second sort, etc.) on the phase chart. Near these elements of the phase chart materials possess unique chemical and physical properties. Therefore development methods of receiving and research of phase forming and properties in NIO-CoO-CuO-Cr2O3 system represent fundamental and practical interest for chemistry and technology of inorganic substances. In this work processes of spinel structure formation in system 0,6 NiCr2O4 – 0,2 CoCr2O4 – 0,2 CuCr2O4 from crystal chemistry positions are considered. Formation of two solid solutions on the basis of nickel (II) chromite – with structure of cubic spinel and with tetragonal distorted structure is established. The influence of cooperative Yahn-Teller effect on processes of a spinel forming and on stabilizing impact of chloride of potassium on process of education of two spinel solid solutions is suggested. Influence of a power factor of cation stabilization in knots of a crystal lattice as one of the important factor in reaction of spinel structure formation is considered.
Keywords: spinels, chromites of transitional elements, Jahn-Teller effect
The investigated nanocomposites are characterized by more uniform distribution of amorphous and crystal phases. An optimal number of crystallization centers - nanoparticles leads to improve mechanical properties of polyethylenes. Introduction of nanofillers into a polymer matrix leads to the formation of cryptocrystalline supermolecular structure by reducing of the thermodynamic threshold of crystallization.
Keywords: low-pressure polyethylene, magnesium spinel, zeolites, nanofiller, the degree of crystallinity, X-ray diffraction, atomic force microscopy