Nature of mixed electrical transport in Ag2O–ZnO–P2O5 glasses containing WO3 and MoO3.

This study reports on the nature of electrical transport and role of structural changes induced by different type and content of TMO in Ag–containing glasses of x TMO–(30–0.5 x )Ag 2 O–(30–0.5 x )ZnO–40P 2 O 5 (TMO = MoO 3 /WO 3 , 0 ≤  x  ≤ 60 mol%) composition. Raman spectra show clustering of WO 6 units in glasses with high WO 3 content while the addition of MoO 3 induces a gradual change of MoO 6 octahedra to MoO 4 tetrahedra both being cross-linked with phosphate units without clustering. For WO 3 glasses, minimum in DC conductivity is observed at 30–40 mol% of WO 3 for temperatures from 303 to 513 K, followed by an increase in conductivity with further WO 3 addition due to an increase in polaronic contribution. Observed turnover suggests a distinct transition from predominantly ionic to predominantly polaronic transport. On the contrary, for MoO 3 glasses, conductivity decreases in the whole mixed compositional range indicating that the nature of transport is dominated by ionic component throughout the measured temperature range. A comparative study of Ag + , Li + , Na + transport in MoO 3 /WO 3 glasses reveals a strong correlation between pre-exponential factor and activation energy, which allows detection of the prevalence of conduction mechanism. Finally, the results demonstrate that Ag 2 O–WO 3 –ZnO–P 2 O 5 glass system is a promising electrically tunable material with significant contributions of ionic or polaronic conductivity depending on composition. [ABSTRACT FROM AUTHOR]