Specific heat of fine copper particles

The specific heats of bulk Cu, CuO powder, and fine Cu particles with average particle sizes around 500 Angstrom were investigated for temperatures between 1 and 20 K, and 300 and 800 K. For temperatures below roughly 20 K, a quadratic temperature term of specific heat bT(2) was observed in fine Cu particles but not in bulk Cu and CuO powder. This is due to the contribution of the two-dimensional surface characteristics of phonons. For temperatures above 300 K, a large exothermal peak was observed for fine Cu particles near 505 K. This is due to the recombination of fine Cu particles to bulk Cu.