Spontaneous Phase Fluctuations of Nanoparticles of Lead in a Silicon Oxide Matrix

Abstract
We present room temperature high-resolution electron microscopy (HREM) data and optical-reflectivity results at λ = 0.6 μm in the temperature range 300-600 K on Pb particles, having dimensions from 15 down to 3 nm and embedded in a matrix of amorphous SiO. HREM gives a clear indication of three different size-dependent regimes for the particles, which are interpreted in terms of spontaneous phase fluctuations occurring for diameters in the range ~ 10-5 nm, where the reflectivity rise typical of the solid-liquid transition is shown to undergo a progressive decrease.