Dielectric–spectroscopic and AC conductivity studies in iron doped layered Na 2Ti 3O 7 ceramics

Abstract

The results of AC electrical conductivity studies in Na 2Ti 3O 7 doped with 0.1 and 1.0 mol% of iron have been reported in the temperature range of 373–773 K. The corresponding log( σ AC T) versus 1000/ T plots have been divided into four distinct regions, namely I, II, III and IV. Lowest temperature region I is attributed to electronic hopping with exchangeable interlayer ionic conduction, in region II associated interlayer ionic conduction is dominated over electronic hopping conduction. Moreover, the conduction in the next region III is due to co-existence of hindered interlayer ionic and suppressed electronic hopping conduction, while conduction in highest temperature region IV is modified interlayer ionic conduction. Dielectric loss (tan δ) and dielectric constant ( ɛ) versus frequency plots at different temperatures have also been described. Furthermore, the results of tan δ and ɛ versus temperature at various frequencies have been reported for iron doped Na 2Ti 3O 7 samples. The losses are the characteristic of dipole mechanism in both the samples. The possibility of ferroelectric phase transition is proposed in this paper.