Tailoring structure for improved sodium mobility and electrical properties in V2O5-Nb2O5-P2O5 Glass(es)-(Ceramics)

This study investigates the influence of structural modifications induced by the introduction of Nb2O5 on the thermal, (micro)structural, and electrical properties of quaternary system 35Na(2)O-10V(2)O(5)-(55-x)P2O5-xNb(2)O(5) (x = 0-40 mol%). Non-monotonic trends in DC conductivity and activation energy are attributed to the facilitating effect of Nb2O5 on the transport of Na (+) ions, confirming the mixed glass former effect. The results demonstrate that the electrical conductivity mechanism is purely ionic, with V2O5 acting as both, glass modifier and network-former with vanadate units being in predominantly 4-fold coordination and without actively participating in the conduction process. Complementary Raman and IR-ATR spectroscopic studies in combination with solid-state impedance spectroscopy (SS-IS) reveal a strong correlation between structural and electrical properties indicating that the enhancement in conductivity is driven by the formation of mixed niobatephosphate glass network. The increase in conductivity is followed by a gradual transition of glass structure from a predominantly phosphate glass network (x & LE; 10, Region I) into a mixed niobate-phosphate glass network (10 & LE; x & LE; 20, Region II). The conductivity increases by a factor of similar to 4.5 within the series reaching the highest value of 3.29 x 10(-10) & omega;(-1) cm(-1) for Nb-20 glass. In the predominantly niobate network (x & GE; 25, Region III), the 3D clustering of NbO6 octahedra hinders the transport of Na (+) ions. The scaling features of the conductivity spectra additionally confirm the ionic mechanism of electrical transport and provide insight into the local dynamics of Na+ ions.

Automated summary

This study examines the effect of introducing Nb2O5 on the thermal, structural, and electrical properties of a quaternary system. The results show that Nb2O5 facilitates the transport of Na(+) ions, leading to non-monotonic trends in DC conductivity and activation energy. The conductivity mechanism is purely ionic, with V2O5 acting as a glass modifier and network-former. The enhancement in conductivity is driven by the formation of a mixed niobatephosphate glass network.