Heavy alkaline earth hydrides (AeH2, Ae = Ca, Sr, Ba) are of interest due to their high hydrogen ion conductivities and potential use in electrochemical devices. AeH2 compounds react with nitrogen forming nitrided compounds. CaH2 forms the nitride hydride (Ca2NH) and Sr and Ba hydride are expected to form a mixture of nitride hydride and imide (Ae[NH]). A variable temperature and atmosphere conductivity sample environment is being developed by St Andrews and ISIS to probe sample conductivity and structure of materials in various gases as a function of temperature. We propose to perform experiments on AeD2 (Ae = Ca, Sr, Ba) in the sample environment, introducing controlled nitrogen atmospheres at temperature while measuring conductivity. Structural data, thermogravimetric and ionic mobility data will be used to elucidate the structure, conduction mechanisms and exchange mechanisms.