Development of special high pressure and high temperature equipment and spectroscopic in situ investigations

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Solution behavior of chemical substances under ammonothermal reaction conditions depends on the system parameters temperature, pressure, type of solvents and the nature and concentration of the mineralizer. The intrinsic reasons for certain behavior are not obtainable by solubility measurements only, since these parameters influence each other. This problem can be solved by an equation of state which links the characteristic variables with the solubility For hydrothermal systems, which are comparable to ammonothermal systems, the Helgeson-Kirkham-Flowers -Tanger equation of state is used for predicting the solubility of different compounds as a function of the above mentioned system parameters . lt is not yet possible to develop an equation of state for the ammonothermal system in the near future, but the goal is fo lay the foundations for this. These measurements with reliable solubility measurements of reactants, such as mass lass measurements, X-rays and UV-VIS and Raman spectroscopy, have to be combined . Solubility measurements should continue to include corrosion experiments with components that are in contact with the ammonothermal medium. The TP 3 provides measurement techniques for all required variables of state, which should be evaluated together with all sub-projects . The insights will be helpful for flow simulations by TP 6. In addition, in situ Raman and UV-VIS spectroscopy can provide valuable information on the immediate molecular environment. With these data and the ex situ data from TP 2 of the intermediates, the reaction mechanisms of nitride formation shall be elucidated. This also includes the measurement of the newly discovered pathways to the ternary and binary nitrides of TP 1 and TP 2.