A scanning AC calorimetry technique for the analysis of nano-scale quantities of materials
We present a scanning AC nanocalorimetry method that enables calorimetry measurements at heating and cooling rates that vary from isothermal to 2 × 10^3 K/s, thus bridging the gap between traditional scanning calorimetry of bulk materials and nanocalorimetry. The method relies on a micromachined nanocalorimetry sensor with a serpentine heating element that is sensitive enough to make measurements on thin-film samples and composition libraries. The ability to perform calorimetry over such a broad range of scanning rates makes it an ideal tool to characterize the kinetics of phase transformations or to explore the behavior of materials far from equilibrium. We demonstrate the technique by performing measurements on thin-film samples of Sn, In, and Bi with thicknesses ranging from 100 to 300 nm. The experimental heat capacities and melting temperatures agree well with literature values. The measured heat capacities are insensitive to the applied AC frequency, scan rate, and heat loss to the environment over a broad range of experimental parameters.
Additional Information© 2012 American Institute of Physics. Received 13 June 2012; accepted 9 October 2012; published online 5 November 2012. The authors would like to thank Jim MacArthur for design and fabrication of the data acquisition system. The work presented in this paper was supported by the Air Force Office of Scientific Research under Grants FA9550-08-1-0374 and FA9550-12-1-0098, and by the Materials Research Science and Engineering Center at Harvard University. It was performed in part at the Center for Nanoscale Systems, a member of the National Nanotechnology Infrastructure Network, which is supported by the National Science Foundation under NSF Award ECS-0335765. The Center for Nanoscale Systems is part of the Faculty of Arts and Sciences at Harvard University.
Published - RevSciInstrum_83_114901.pdf