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Insights on the relationship between structural and electrical properties in sodium vanadium niobium phosphate glasses

Ever since the alkali phosphate-based glasses have emerged as promising candidates for application as electrolytes and/or electrode materials in solid- state batteries, research has largely focused on the elucidation of the relationship between composition, structure, and electrical properties in order to enhance the conductivity in these glasses. (1) Numerous studies have shown that the ionic transport in oxide glasses can be strongly affected by the addition of a second glass-former, resulting in a non-linear variation of ionic conductivity with a maximum (or minimum) at a certain glass composition, known as the mixed glass former effect (MGFE). (2) While MGFE has been extensively studied in glasses with conventional glass-formers (B2O3, SiO2, P2O5, GeO2), the glass systems where a conventional glass-former is substituted by the conditional one, such as transition metal oxide (TMO) are scarce. (3, 4) In the presented study, two series of glasses from the system Na2O–V2O5–P2O5–Nb2O5 are prepared and investigated to verify the MGFE in the presence of two conditional glass formers, V2O5 and Nb2O5. In both series, the content of V2O5 is kept constant, while P2O5 is gradually replaced by Nb2O5. The glasses are synthesized by the melt-quenching technique and their amorphous character is confirmed by PXRD. The thermal behaviour of the glasses is analyzed by DTA, while their structural properties are evaluated by SEM-EDS analysis and IR-ATR spectroscopy. The electrical properties of the prepared glasses are investigated by solid- state impedance spectroscopy (SS-IS) in a wide range of frequencies (0.01 Hz – 1 MHz) and temperatures (-90 °C – 240 °C). The relationship between the structural changes that occur upon glass-formers exchange, and certain physico- chemical properties of these glasses is discussed in detail. ACKNOWLEDGEMENTS: This work is supported by the Croatian Science Foundation, POLAR-ION-GLASS project IP-2018–01–5425. 1. Musgraves, J. D., Hu, J., Calvez, L., Springer Handbook of Glass, Springer Nature, Switzerland, 2019, p. 553–594. 2. Storek, M., Adjei-Acheamfour, M., Christensen, R., Martin, S. W., Böhmer, R., J. Phys. Chem. B 120 (2016) 4482–4495. 3. Renka, S., Pavić, L., Tricot, G., Mošner, P., Koudelka, L., Moguš-Milanković, A., Šantić, A., Phys. Chem. Chem. Phys. 23 (2021) 9761–9772. 4. Zaini, N. A., Mohamed, S. N., Mohamed, M., Materials 14 (2021) 3710–3717.

glass ; glass-ceramic ; structural properties ; electrical properties

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