Exploring the Effect of V2O5 and Nb2O5 Content on the Structural, Thermal, and Electrical Characteristics of Sodium Phosphate Glasses and Glass–Ceramics

Scientific paper - Original scientific paper

• Author: Sara Marijan
• Author: Teodoro Klaser
• Author: Marija Mirosavljević
• Author: Petr Mošner
• Author: Ladislav Koudelka
• Author: Željko Skoko
• Author: Jana Pisk
• Author: Luka Pavić
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

Na-V-P-Nb-based materials have gained substantial recognition as cathode materials in high-rate sodium-ion batteries due to their unique properties and compositions, comprising both alkali and transition metal ions, which allow them to exhibit a mixed ionic–polaronic conduction mechanism. In this study, the impact of introducing two transition metal oxides, V2O5 and Nb2O5, on the thermal, (micro)structural, and electrical properties of the 35Na2O-25V2O5-(40 − x)P2O5 − xNb2O5 system is examined. The starting glass shows the highest values of DC conductivity, σDC, reaching 1.45 × 10−8 Ω−1 cm−1 at 303 K, along with a glass transition temperature, Tg, of 371 °C. The incorporation of Nb2O5 influences both σDC and Tg, resulting in non-linear trends, with the lowest values observed for the glass with x = 20 mol%. Electron paramagnetic resonance measurements and vibrational spectroscopy results suggest that the observed non-monotonic trend in σDC arises from a diminishing contribution of polaronic conductivity due to the decrease in the relative number of V4+ ions and the introduction of Nb2O5, which disrupts the predominantly mixed vanadate–phosphate network within the starting glasses, consequently impeding polaronic transport. The mechanism of electrical transport is investigated using the model-free Summerfield scaling procedure, revealing the presence of mixed ionic–polaronic conductivity in glasses where x < 10 mol%, whereas for x ≥ 10 mol%, the ionic conductivity mechanism becomes prominent. To assess the impact of the V2O5 content on the electrical transport mechanism, a comparative analysis of two analogue series with varying V2O5 content (10 and 25 mol%) is conducted to evaluate the extent of its polaronic contribution.

• Keywords (english): phosphate glasses; phosphate glass–ceramics; (micro)structure–property relationship; PXRD; SEM-EDS; EPR; vibrational spectroscopy; impedance spectroscopy; electrical properties
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: International Journal of Molecular Sciences
• Numbering: vol. 25, no. 5, 3005
• e-ISSN: 1422-0067
• DOI: https://doi.org/10.3390/ijms25053005
• URN:NBN: urn:nbn:hr:217:370725
• Publication: 2024-03-05
• Project: Number: IP-2018-01-5425; Title (croatian): Detaljan uvid u mehanizme polaronske i ionske vodljivosti u oksidnoj staklo-(keramici); Acronym: POLAR-ION-GLASS; Leader: Ana Šantić; Jurisdiction: Croatia; Funding stream: Research Projects
• Document URL: https://www.mdpi.com/1422-0067/25/5/3005
• Type of resource: Text
• Access conditions: Open access
• Public note: © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Received: 16 February 2024. Revised: 28 February 2024. Accepted: 1 March 2024. Published: 5 March 2024.
• Created on: 2024-07-24 10:31:33