[en] Nanoscale cobalt clusters have been synthesized in an amorphous silica matrix by implanting high energy cobalt ions (2 MeV, Co²⁺) with various doses. Surface acoustic radial vibration (phonons) modes confined to these cobalt nanoclusters have been detected using the low-frequency Raman scattering spectroscopy. Postannealing the ion implanted silica samples in a high vacuum atmosphere has led to significant growth of the cobalt nanoclusters in the silica glass matrix. Using suitable mechanism for the growth of the nanoclusters, activation energy for the diffusion of cobalt atoms in the silica matrix is calculated to be about 0.20 eV. Diffusion of the implanted cobalt atoms in the silica matrix during postannealing is further examined from the Rutherford backscattering measurements