The opposing effect of gamma irradiation on proton and sodium ion conduction in Na2Ti3O7 and its defective analog
| dc.contributor.author | Maluangnont, Tosapol | |
| dc.contributor.author | Chaithaweep, Kanokwan | |
| dc.contributor.author | Sangtawesin, Tanagorn | |
| dc.contributor.author | Vittayakorn, Naratip | |
| dc.date.accessioned | 2026-08-06T10:56:25Z | |
| dc.date.available | 2026-08-06T10:56:25Z | |
| dc.date.issued | 2026-10-01 | |
| dc.description.abstract | It is known that γ-irradiation of Na<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf> induces Na <sup>+</sup> ion deintercalation, oxygen-vacancy formation, and proton/water incorporation, yielding the defective phase Na<inf>2- x </inf>H<inf>0.5 x </inf>Ti<inf>3</inf>O<inf>7-0.5 x </inf>(OH)<inf>0.5 x </inf> with multiple charge carriers. Although Na<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf> is a well-studied ion conductor, charge-transport details in its γ-irradiated analogs remain limited. Here, we report their AC conductivity and dielectric properties under a temperature cycle (RT→350 °C→RT). Proton conduction dominates at ambient temperature but diminishes upon heating. This produces a dehydration-driven increase of resistivity known as the apparent Positive Temperature Coefficient of Resistivity (PTCR) effect, consistent with the Heywang model recently applied to water-adsorbing ceramics. Proton conductivity increases with γ-irradiation dose up to 200 kGy, then decreases at 400 kGy due to excessive structural disorder. At high temperatures, Na<sup>+</sup> ion conduction prevails and follows Arrhenius behavior, with activation energy decreasing with dose. This discrepancy might be understood considering that Na<sup>+</sup> ion conduction is governed primarily by its concentration rather than mobility; excessive doses lower activation energy but deplete Na<sup>+</sup> ions and decrease conductivity. Dielectric-loss fitting using Jonscher's universal dielectric response (UDR) indicates that proton-transport pathways are sensitive to thermal history, whereas Na<sup>+</sup> ion conduction exhibits low-frequency dispersion (LFD) across all conditions. | |
| dc.identifier.citation | Radiation Physics and Chemistry, 247, 2026 | |
| dc.identifier.doi | 10.1016/j.radphyschem.2026.114006 | |
| dc.identifier.issn | 0969806X | |
| dc.identifier.other | 2-s2.0-105038638815 | |
| dc.identifier.uri | https://dspace.kmitl.ac.th/handle/123456789/18327 | |
| dc.source | Radiation Physics and Chemistry | |
| dc.title | The opposing effect of gamma irradiation on proton and sodium ion conduction in Na2Ti3O7 and its defective analog | |
| dc.type | Article |