CHARACTERIZATION BY RUTHERFORD BACKSCATTERING, ELASTIC RECOIL AND NUCLEAR-REACTION ANALYSIS OF NEAR-SURFACE MODIFICATIONS OF GLASSES SUBMITTED TO A DC POTENTIAL

The near-surface modifications of glasses with different compositions were studied by the combination of three nuclear techniques for surface analysis: the resonant nuclear reaction Na-23(p,alpha)Ne-20 at E(r) = 591.6 keV, 2.2 MeV He-4 elastic recoil detection analysis and Rutherford backscattering spectrometry. Glass samples were submitted to a DC potential during different time intervals and temperatures. -The influence of the electrodes on the surface modifications was studied. The modified layer thickness was related to the total charge which passed through the sample during the treatment. Continuous recording of the current flowing through the glass shows that, for a fixed voltage, there is a general decrease in the current with time. This behaviour was related to the surface composition modifications determined by the nuclear techniques.