Samples of silica were implanted with Nd ions to doses ranging from 5 x 1015 to 9 x 1016/cm2 and were annealed at temperatures of up to 1100C. Changes in the Nd depth profiles were monitored by means of Rutherford back-scattering spectroscopy. Diffusion was observed at an annealing temperature of 1100C, but there was no change at lower annealing temperatures. There was a driving force away from the surface, and a maximum equilibrium Nd concentration of about 10%.

A.Shojai, G.T.Reed, C.Jeynes: Journal of Physics D, 1992, 25[8], 1280-3