Thermodynamics and kinetics of non-autonomous phase formation in nanostructured materials with variable functional properties

Abstract

The review addresses physico-chemical aspects of interaction between macro-, micro-and nano-structured units of matter with the analysis of interface and grain boundary entities (nonautonomous phases) mechanisms and formation, as well as methods of their control in order to achieve the desired functional properties of nanostructured materials. Construction of these materials involves identification of thermodynamic and kinetic regularities in the organization processes, state and genesis parameters of nonautonomous phases formed as specific nanosized structures in a limited space between the macroscopic volume phases and with the limited amount of substance, which differ significantly on their properties, structure and composition from the appropriate characteristics of volume phases. Studying them is based on the application and development of theoretical and experimental methods of non-equilibrium thermodynamics, chemical kinetics, nonlinear dynamics and fractal analysis to determine the conditions of self-organization or materials directed synthesis with a high content of nonautonomous phases.

Platinum Group Elements in Arsenopyrites and Pyrites of the Natalkinskoe Gold Deposit (Northeastern Russia)

“…The reason for this phenomenon involves the features of the crystal growth mechanism and the dualism of the element distribution coefficient in the mineral-hydrothermal solution system, which is an order of magnitude higher for NAP compared to the crystal volume [38,39]. Non-autonomous phases are extremely important, but they are still rarely considered components of synthetic materials and minerals, the geochemical role of which lies in their ability to accumulate impurity elements in ultra-high contents [52]. Such phases occur on the surface of a growing crystal due to the chemical modification and structural reconstruction of its surface layer, which is in local equilibrium with a supersaturated solution.…”

Sol-gel synthesis and the investigation of the properties of nanocrystalline holmium orthoferrite

“…For example, they can be compatible with biological materials [5], their nanoparticles can be used as small probes [6][7][8][9], which would allow registering the cellular processes without affecting their course. In addition, particles of the nanometer size range are used to increase the density of magnetic recording of information [10][11][12], production of the transformer coils and other electrical devices with high efficiency [10,13,14].…”

“…The presented method allows production of highly dispersed powders, fibers or thin films from solutions at temperatures lower than in the case of traditional solid-phase systems [19][20][21][22][23][24]. Such materials can be imparted with completely new functional characteristics, completely different from the characteristics of conventional materials by controlling the composition, size, and shape of nanocrystals [14,25].…”

The minimum size of oxide nanocrystals: phenomenological thermodynamic vs crystal-chemical approaches

“…The interest in determining the minimum possible size of crystals is determined by the possibility of creating promising functional and structural nanomaterials based on such crystalline particles [83][84][85][86][87]. One such widely used class of nanomaterials is represented by oxide nanocrystalline materials [83][84][85][86][87]. At the same time, literature offers no systematic analysis of the influence of chemical composition, features of the crystal structure, and of the methods and conditions of the nanocrystals synthesis on the possible limit values of their size.…”