A nanocalorimeter designed for use with high-resolution transmission electron microscopy

Nanocalorimetry is a thermal analysis technique utilizing microfabricated sensors capable of characterizing phase transformations and chemical reactions both isothermally or at fast heating and cooling rates when operated in a scanning mode. Here, a nanocalorimeter was designed to operate in a transmission electron microscope (TEM) holder compatible with TEMs with a narrow pole piece gap. The nanocalorimeters have an electrical connection design to enable in situ TEM observation during high-rate thermal measurements. Both 10 nm alumina and 20 nm silicon nitride membranes were realized as TEM observation windows, to allow for high resolution and high-speed imaging. For certain specimens, the nanocalorimeters may be fabricated with small perforations so the specimen may be imaged over vacuum without any support layer, as demonstrated for a 25 nm thick gold film. Elimination of the amorphous silicon nitride under the TEM observation region reduces the background signal. Preliminary measurements demonstrate the versatility of the nanocalorimeter for in situ TEM observation. Synchronizing nanocalorimetry with a high-frame-rate direct electron detector further extends the measurement capability to couple thermal analysis with the evolution of microstructure.