Studying materials and processes in liquid environments by electron microscopy has recently become a major topic of interest across a wide range of disciplines with the arrival of high-performance liquid cell TEM holders and atmospheric scanning electron microscopy. As an example studying the dynamics of crystal growth and dissolution with nanometer or even atomic level resolution clearly describes a “promised land” of Materials Science catching the underlying mechanism in the act while giving the freedom of mixing materials and solutions and recording imaging data. Furthermore progress in holder design and detector technology has made it possible to perform element analysis using energy dispersive X-ray spectroscopy in liquid cell TEM. However, it has also become clear that care has to be taken when interpreting images and videos recorded from materials in liquid media since the interactions between electron beam and sample can be complex and significant and hence the validity of data depends on the thoroughness by which a clear distinction is made between “genuine” processes and those partially or solely triggered or caused by the electron beam. On this background my presentation explores potentials of liquid cell TEM and ASEM and their current limitations for understanding processes e.g. in biomineralization and crystal growth focusing in particular on the kinetics of precious metal nanoparticle, carbonate and sulphate formation and dissolution in the presence and absence of additives. First data will be presented on Mg carbonate precipitation obtained by a novel heating liquid cell TEM holder allowing for the controled realisation of temperatures between 25˚C and 100 ˚C.
