Nanocalorimetry: Door opened for in situ material characterization under extreme non-equilibrium conditions

The past two decades have witnessed the rapid development of nanocalorimetry, a novel materials characterization technique that employs micromachined calorimetric sensors. The key advances of this technique are the ultrahigh scanning rate, which can be as high as 10(6) K/s, and the ultrahigh heat capacity sensitivity, with a resolution typically better than 1 nJ/K. Nanocalorimetry has attracted extensive attention in the field of materials science, where it is applied to perform quantitative analysis of rapid phase transitions. This paper reviews the development of nanocalorimetry over the last three decades and summarizes its applications to various materials ranging from polymers to metals. The glass transition and crystallization of non-crystalline materials, melting and solidification of metallic droplets, and solid-state phase transitions of thin films are introduced as typical examples. Furthermore, nanocalorimetry coupled with structural characterization techniques, such as transmission electron microscopy and synchrotron X-ray diffraction, is presented. Finally, current challenges and future outlooks for the technique are discussed. Given the unique attributes of the technique, we expect nanocalorimetry to attract increasing attention, especially with regard to characterization of fast phase transitions and evaluation of size effects.