The solubilization of silicates was investigated using kaolin and quartz sand as model substances. The mineral solubilization was studied in the concentration of solubilized Si and Al. The chemical leaching of the silicates was carried out using inorganic and organic acids as well as sodium hydroxide. The process was more effective in the alkine than in the acid p H range. In the acid medinm, oxalic acid showed maximum acidity and a tendency to form complex structures, especially with aluminium, and was most effective in leaching. The microbiological influence on solubilization reactions was tested using a number of microorganisms among them acid, alkali and slime-forming species. The highest. leaching activity was observed in the case of Thiobucillus thiooxiduns, whereas the heterotrophic microorganisms (among them Bacillus muciluginosus) did not exercise D solubilizing effect on the silicates. X-ray phase analysis of leached kaolin samples did not show any differences from the non-leached mineral.

The microstructure as well as the decomposition and crystallization of the Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass ͑MG͒ has been investigated. The effects of the decomposition on the subsequent crystallization are determined. Reduced density function analyses for the MG, and the decomposition and crystallization in the MG have been made by means of electron-diffraction intensity measurement with imaging plate to determine the local atomic structure and its development in the course of the decomposition and crystallization. The microstructural characteristics of the MG are obtained demonstrating the difference between the bulk MG and conventional MG. The origin of the large glass forming ability of the alloy and the effect of the phase separation on the crystallization are discussed based on the obtained local atomic structural information of the MG.

Decomposition and metastable phase formation in the bulk metallic glass matrix composite Zr 56 Ti 14 Nb 5 Cu 7 Ni 6 Be 12Glass transition behavior, crystallization kinetics, and microstructure change of Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass under high pressure

A systematic study was carried out on the equilibrium phases after slow solidification of the Zr41Ti14Cu12.5Ni10Be22.5 alloy. The crystalline microstructure of the slowly cooled melt of the alloy shows “polygons” and “plates” embedded in a fine-grained two-component matrix. To analyze the crystal structure of the different components, microdiffraction technique combining convergent beam electron diffraction and conventional selected-area electron diffraction were used. The stoichiometry of these phases was confirmed by field ion microscopy with atom probe and energy-dispersive x-ray analysis in a transmission electron microscope. The polygons were determined to be cubic (a = 1.185 nm) with space group Fm3m (cF116). The plates were found to be tetragonal (a = 0.37 nm, c = 1.137 nm) with space group I4/mmm (tI6). Its composition is (Cu + Ni)(Zr + Ti)2. One phase of the fine-grained two-component matrix was rich in Ti and poor in Be; the other one was rich in Be and poor in Ti. The Ti-rich phase was determined to be hexagonal (a = 0.536 nm, c = 0.888 nm) with space group P63/mmc.

Since the early 1950's the use of Germanium has been continuously growing as new applications are being developed. Its first commercial usage as the main material, from which the semiconductors were made, was later replaced by Silicon. The applications were then shifted to a key component in fiber optics, infrared night vision devices and space solar cells, as well as a polymerization catalyst for polyethylene terephthalate (PET). With the advance development in new technologies, the attentions have been brought back to Germanium due to its excellent semiconductor properties. New applications on the field of high efficiency solar cells, SiGe based chips, LED technologies, etc., are being developed and show a great potential. According to DERA (Deutsche Rohstoffagentur/German Mineral Resources Agency), the demand for Ge will grow considerably by 2030, pushed mostly by the increase in the fiber optics market and advanced materials sector [1]. Therefore, this paper focuses on an overview of the production chain of Germanium, especially from its concentrate up to the single crystal growth of its valuable ultra-pure metallic form to be used in high technological applications.