Phase Equilibria in the System CaO-SiO2-La2O3-Nb2O5 at 1400 °C

CaO-SiO2-La2O3-Nb2O5 system is of great significance for the pyrometallurgical utilization of Bayan Obo tailing resources. In the present work, the phase equilibrium of this quaternary system at 1400 °C was determined by a thermodynamic equilibrium experiment. On the basis of the recently determined CaO-La2O3-Nb2O5 phase diagram, some boundary surfaces of primary phase fields of CaO-SiO2-La2O3-Nb2O5 phase diagram were modified; then, the 1400 °C isothermal surface in the primary phase fields of SiO2, CaNb2O6, Ca2Nb2O7, and LaNbO4 was constructed, respectively. On this basis, CaO-SiO2-Nb2O5 pseudo-ternary phase diagrams with w(La2O3) = 5%, 10%, 15%, and 20% were determined, respectively. Considering the importance of equilibrium crystallization reaction type, we proposed a new rule named Tangent Line Rule to judge the univariant reaction type in the quaternary phase diagram. By applying Tangent Line Rule and Tangent Plane Rule previously proposed, some univariant and bivariant crystallization reaction types in the CaO-SiO2-La2O3- Nb2O5 phase diagram were determined, respectively. The current work can provide original data for the establishment of a thermodynamic database of Nb-bearing and REE-bearing slag system; the proposed Tangent Line Rule will promote the application of a spatial quaternary phase diagram.

Phase evolution of Cu2ZnSnS4 (CZTS) nanoparticles from in situ formed binary sulphides under solvothermal conditions

Cu2ZnSnS4 (CZTS) nanocrystals form both by direct nucleation and growth and by conversion of binary sulphides into the quaternary phase via internal recrystallization processes.

A Status Review on Cu2ZnSn(S, Se)4-Based Thin-Film Solar Cells

Photovoltaics has become a significant branch of next-generation sustainable energy production. Kesterite Cu2ZnSn(S, Se)4 (copper-zinc-tin-(sulfur, selenium) or CZTS(Se)) is considered one of the most promising, earth-abundant, and nontoxic candidates for solar energy generation over the last decade. However, shallow phase stability of the quaternary phase and the presence of various secondary phases and defects are the main hindrances in achieving the target device performance. This paper summarizes various approaches to synthesize the CZTS absorber layer and the CdS n-type material layer. Besides, different CZTS solar cell device structures, as well as a comprehensive review of secondary phases and defects, have been illustrated and discussed. At last, this review is intended to highlight the current challenges and prospects of CZTS solar cells.

Quaternary phase diagrams as a tool for ionic cocrystallization: the case of a solid solution between a racemic and enantiopure ionic cocrystal

Quaternary phase diagram of ionic cocrystals with solid solution formation is generated and dissolution surface is depicted clearly by contour lines.

ADAPTATION OF THE METHOD OF STRUCTURAL-MORPHOMETRIC ANALYSIS TO THE GIS ENVIRONMENT FOR PALEOGEOMORPHOLOGICAL STUDIES OF THE KANIV DNIEPER

Kaniv Dnieper area is a unique region that has evolved through the Neogene-Quaternary phase. The application of geological and geomorphological methods, remote sensing data and GIS made it possible to identify the genetic relationship between the processes of geomorphogenesis and tectogenesis within the Kaniv Dnieper region, to build a number of geological and geomorphological models. The methodology of structural-morphometric analysis is adapted to the GIS and the process of cartometric constructions is automated. An algorithm for creating order maps of valleys and basal surfaces has been developed. Basal surfaces are complex surfaces that combine local erosion bases and express the total movements of the earth's crust over various time intervals. A study of the morphogenesis and tectogenesis of the territory of the Kaniv Dnieper region showed that the neotectonic movements within this region had a differentiated character. Five stages of tectonic evolution were determined during the Neogene-Quaternary stage of its development. Hypsometry of basic surfaces of five orders was investigated, and a detailed comparison of the morphology of single-order surfaces has been made. On the basis of the obtained data on the nature of the surfaces, absolute and relative elevations, the nature of the isobasite pattern, the geomorphological structure of each stage has been analyzed in detail. The conducted studies revealed a regular relationship between the relief and tectonics.