In this thesis the calculation of the Fe-N binding and the N diffusion as well as the equations of state of Ge_3N_4 and Sn_3N_4 are described. (HSI)SIGLEAvailable from: http://eldorado.uni-dortmund.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman