DIFFUSIVE BARRIER IN SILVER PHOSPHATE AND SILVER BOROPHOSPHATE GLASSES

Dielectric measurements are carried out on [60 Ag2O-x B2O3-(40 - x) P2 O5] glasses in the frequency and temperature range 10(-3) to 10(5) Hz and 120 to 400 K, respectively. The observed dielectric data show an i nterfacial barrier at the metal-glass contact and reveal a barrier rel axation time tau almost-equal-to 0.1 s, barrier capacitance C(s) almos t-equal-to 4 x 10(-6) F, barrier width d(s) almost-equal-to 8.8 nm, an d dc conductivity sigma(dc) almost-equal-to 1.67 x 10(-3) OMEGA-1 m-1 for the [60 Ag2O-8 B2O3-32 P2O5] glass at room temperature. A capaciti ve contribution from BPO4 and PO4 groups in the bulk along with an int erfacial layer capacitance is suggested to be responsible for the larg e dispersion observed in C(omega). The activation energies for three d ifferent glass compositions are found to be (0.48 +/- 0.02), (0.40 +/- 0.02), and (0.50 +/- 0.02) eV.