Enhanced specific-heat-capacity (cp) measurements (150–300 K) of nanometer-sized crystalline materials

Abstract

Nanometer-sized crystalline materials are polycrystals with a crystal size of a few (1–10) nano-meters. Because of the small crystallite size, these materials consist of two components with comparable volume fractions: a crystalline component comprising all atoms located in the lattice of the crystallites (grains) and an interfacial component formed by all atoms situated in the interfaces (grain boundaries). In order to test the influence of the interfacial component on the specific heat $c_p$, nanometer-sized crystalline Pd (6 nm crystal size) and Cu (8 nm crystal size) were measured and the results compared with the $c_p$ values for polycrystalline Pd, Cu, and a corresponding ${\mathrm{Pd}}_{72}$ ${\mathrm{Si}}_{18}$ ${\mathrm{Fe}}_{10}$ metallic glass. Specific-heat measurements in the temperature range between 150 and 300 K revealed that the $c_p$ values of nanometer-sized crystalline Cu were about 10% higher than in the polycrystalline state and that the values for nanometer-sized crystalline Pd were about 40% higher than in crystalline Pd or 30% higher than in the metallic glass ${\mathrm{Pd}}_{12}$ ${\mathrm{Si}}_{18}$ ${\mathrm{Fe}}_{10}$.