Speaker
Description
Cryogenic sample preparation for atom probe tomography is becoming more widespread and has allowed the analysis of many new material systems including frozen liquids, solid/liquid interfaces and soft matter. Much of the work has been adapted from the life sciences where temperature control is very stringent and restrict the user to temperatures below the vitrification point of water, effectively requiring the use of liquid nitrogen. Using liquid nitrogen in this manner requires extensive modifications to instrumentation and restriction in location and times of operation due to health and safety regulations. Many systems of interest to material science requiring cryogenic sample preparation do not require liquid nitrogen temperature and so in these cases, it is possible to avoid the use of liquid nitrogen and instead use an alternative solid state cooling system such as a Peltier cooled stage. There are a number of commercial systems that provide cooling down to -100°C and can be installed on instrument stages with minimal feedthrough requirements, making this an option for non cryogenic specialist facilities to engaged in cryogenic sample preparation. In order to determine whether this approach is appropriate for a given material system, the effect of sample preparation at various temperatures needs to be carried out. Commercially pure titanium is known to form hydrides during room temperature Ga FIB sample preparation for APT and TEM and so typically Ga FIB sample preparation is carried out using liquid nitrogen temperatures. In this presentation we discuss the effects of Ga FIB preparation of APT samples from commercially pure titanium at a variety of cryogenic temperatures within the reach of a Peltier stage (between room temperature and -100°C) by using a nitrogen gas cooled stage combined with a stage heater.
