HEAT-CAPACITY ANOMALY OF AG ULTRAFINE PARTICLES AT LOW-TEMPERATURES

The heat capacity of ultrafine particles of silver (21 nm) was measured by an adiabatic method between 1.6 K and 13 K. The capacity was smaller than that of bulk Ag at lower temperatures and larger at higher temperatures. A peak and a hump were observed at 1.8 K and 3.4 K in the curve of temperature dependance of heat capacity. A trough and sharp cutoff were found in the curve at 2.2 K and 1.6 K. By sintering the sample, periodical multiple peaks appeared in the curve at lower temperatures and heat capacity at higher temperatures decreased to the same value as that of bulk. These phenomena are interpreted in terms of resonance of lattice vibration in a particle. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.