Nanocalorimetry measurements of materials having small dimensions

Abstract

Summary form only given. The trend in microelectronic technology is toward nanometer size scales. Thermodynamic properties of material having small nanometer dimensions can be considerably different as compared to material in bulk form (e.g., the reduction of melting point). This occurs because of the tremendous influence of the surface energy. Calorimetry is the standard experimental technique used to measure thermodynamics properties such as the melting point and the heat of fusion. However, conventional differential scanning calorimetry (DSC) techniques are extremely difficult to apply to the study of small structures because the total amount of heat generated during the transformation is too small as compared with the background beat capacity of the calorimeter. In this talk I=9211 discuss a new nanocalorimetry technique which we have developed for the measurement of nanoscale systems. This nanocalorimeter is fabricated using standard MEMS thin film techniques and it has the capability of measuring the dynamics of the energy exchange at the level of 0.2 nanojoule. This technique is so sensitive that it can easily measure the melting process of 1 Angstrom of Sn which has been deposited on a Si-N surface. Results of specific materials studies will be discussed including the size-dependent melting point depression of small particles of Sn and Al and preliminary work on the coalescence of small clusters.