The formation and crystal growth of black Phosphorus by a transport reaction has not been clarified to date. We propose to investigate both at D20 with an in situ experiment. Black Phosphorus is an interesting candidate as anode material for Lithium- and Sodium-ion batteries. Therefore, the exploration of the formation and growth is essential to understand its reactivity and electrochemical behaviour, as well as the stability in relation to its other allotropes.A mixture of red Phosphorus will be reacted with tin and tin iodide enclosed in a silica glass ampoule. By heating it up to 923 K and holding it at lower temperatures the formation of black Phosphorus will be initiated. The growth will be investigated under isothermally conditions in two consecutive experiments at 773 K and 723 K afterwards. A furnace with a Vanadium heating element, belonging to D20 will be used. The reaction rate as well as the growth kinetics will be analysed to achieve a crystal growth model of the formation of black Phosphorus.