A comprehensive study was made on biasing the silver metaphosphate glass with a dc pulse train, by using sputtered aluminum or evaporated aluminum as the anode. Oxidation of aluminum proceeded at the anode-glass interface, and relevant polarization and depolarization peaks were seen at the onsets of biasing and off biasing, respectively. It was suggested tentatively that the polarization arose from orientational motion of the P-O dipoles within the oxide, with 54+/-1 kJ/mol as the activation energy for relaxation. (C) 2003 Kluwer Academic Publishers.