In situ thermal desorption of H2 from LiNH2–2LiH monitored by environmental SEM

This article describes in situ heating and observation of a LiNH2–2LiH mixture in an environmental scanning electron microscope (ESEM). The LiNH2–2LiH mixture showed extensive morphological changes with heating and attendant hydrogen desorption. Static images and real-time movies were obtained during the dehydrogenation process. H2 evolution commences at ∼150 °C (LiNH2 + 2LiH → Li2NH + H2 + LiH), and continues until ∼410 °C. Dramatic morphological changes are observed at 220 and 410 °C (Li2NH + LiH → Li3N + H2). The material converts to a microcrystalline phase at higher temperatures (>500 °C). The observed H2 desorption and morphological changes occur at temperatures in good agreement with those measured by complementary analytical methods. This is the first time the major structural and morphological changes attendant on H2 loss from this system have been observed in situ and in real time.