Die vorliegende Arbeit befasst sich mit Untersuchungen zur Herstellung der Erdalkalimetallchlorate und zu den Lösungsgleichgewichten in den reziproken Salzpaaren MCl2 + 2NaClO3 = M(ClO3)2 + 2NaCl/H2O (M = Mg2+, Ca2+, Sr2+, Ba2+) bei 25°C, 50°C und 75°C. Neben den Löslichkeiten und Bodenkörperparagenesen sind die Dichten und Viskositäten bestimmt worden. Auf der Basis der erarbeiten Daten erfolgte die Bilanzierung der Herstellungsprozesse der Erdalkalimetallchlorate durch reziproke Umsetzung. Zusammenfassend kann eingeschätzt werden, dass mit etwa 0,2 bis 0,5 kg wasserfreies Chlorat pro kg Umlauflösung durchaus effektive Prozesse der polythermen reziproken Umsetzung vorliegen. Über die IR- und Raman-Spektroskopie und die Thermoanalyse wurden die Erdalkalimetallchlorate bzw. Erdalkalimetallchlorat-Hydrate näher charakterisiert, u.a. bezüglich ihres Zersetzungsverhaltens bis zum Erdalkalimetallchlorid.

The main focus of the present work was the Ge-rich part of the binary Ba – Ge system, in which by inspecting the behavior of the clathrate-I Ba8Ge43 under pressure, several new phases were found. The new phases in this system have the following compositions: BaGe3 (with two modifications), BaGe5, BaGe5.5 and BaGe6, therefore they are quite close in composition range: 75% - ~85% at. Ge. Concerning the conditions required for the synthesis of each phase, several combinations of temperature and pressure were employed in order to find a stability range. It was possible to establish such a formation range for all phases. In some cases two phases were found for a given conditions and in many other cases three or more phases were found to coexist. Thus, the stability range of pressure and temperature for single phase formation turned out to be very narrow. By inspecting of some structural features, for instance the interatomic distances, it is found that the average of the Ge – Ge distances change in line with the composition, i.e. the shorter contacts belong to BaGe6 while the longer distances are present in BaGe3 (both modification). An opposite trend is observed for the calculated density of each phase (neglecting the tI32 form of BaGe3): the lower density is found for BaGe3 and the denser compound is found to be BaGe6. Of course this is not coincidence, since due to the Ge content, BaGe6 has the largest molar mass. Similarly, by examining the density as a function of the interatomic distance. In such case, the denser compound is characterized by shorter Ge – Ge contacts, while the less dense phase holds the longest Ge – Ge contacts. This is in agreement with the building motifs within each crystal structure: columns in BaGe3 (open framework) passing through layers in BaGe5, ending in a three-dimensional network (closed framework) in BaGe6.

The main focus of the present work was the Ge-rich part of the binary Ba – Ge system, in which by inspecting the behavior of the clathrate-I Ba8Ge43 under pressure, several new phases were found. The new phases in this system have the following compositions: BaGe3 (with two modifications), BaGe5, BaGe5.5 and BaGe6, therefore they are quite close in composition range: 75% - ~85% at. Ge. Concerning the conditions required for the synthesis of each phase, several combinations of temperature and pressure were employed in order to find a stability range. It was possible to establish such a formation range for all phases. In some cases two phases were found for a given conditions and in many other cases three or more phases were found to coexist. Thus, the stability range of pressure and temperature for single phase formation turned out to be very narrow. By inspecting of some structural features, for instance the interatomic distances, it is found that the average of the Ge – Ge distances change in line with the composition, i.e. the shorter contacts belong to BaGe6 while the longer distances are present in BaGe3 (both modification). An opposite trend is observed for the calculated density of each phase (neglecting the tI32 form of BaGe3): the lower density is found for BaGe3 and the denser compound is found to be BaGe6. Of course this is not coincidence, since due to the Ge content, BaGe6 has the largest molar mass. Similarly, by examining the density as a function of the interatomic distance. In such case, the denser compound is characterized by shorter Ge – Ge contacts, while the less dense phase holds the longest Ge – Ge contacts. This is in agreement with the building motifs within each crystal structure: columns in BaGe3 (open framework) passing through layers in BaGe5, ending in a three-dimensional network (closed framework) in BaGe6.

Die vorliegende Arbeit befasst sich mit Untersuchungen zur Herstellung der Erdalkalimetallchlorate und zu den Lösungsgleichgewichten in den reziproken Salzpaaren MCl2 + 2NaClO3 = M(ClO3)2 + 2NaCl/H2O (M = Mg2+, Ca2+, Sr2+, Ba2+) bei 25°C, 50°C und 75°C. Neben den Löslichkeiten und Bodenkörperparagenesen sind die Dichten und Viskositäten bestimmt worden. Auf der Basis der erarbeiten Daten erfolgte die Bilanzierung der Herstellungsprozesse der Erdalkalimetallchlorate durch reziproke Umsetzung. Zusammenfassend kann eingeschätzt werden, dass mit etwa 0,2 bis 0,5 kg wasserfreies Chlorat pro kg Umlauflösung durchaus effektive Prozesse der polythermen reziproken Umsetzung vorliegen. Über die IR- und Raman-Spektroskopie und die Thermoanalyse wurden die Erdalkalimetallchlorate bzw. Erdalkalimetallchlorat-Hydrate näher charakterisiert, u.a. bezüglich ihres Zersetzungsverhaltens bis zum Erdalkalimetallchlorid.