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Electrical and structural properties of Na2O-V2O5-P2O5-Nb2O5 glasses

With the growing interest in the development of solid-state batteries, the study of the electrical properties of alkali phosphate-based glasses has attracted considerable attention due to their great potential for application as electrolytes and/or electrode materials. In particular, research has focused on the improvement of ionic conductivity in these glasses, which is achieved by introducing a second glass-former that causes non-linear variation of ionic conductivity, a phenomenon known as mixed glass former effect (MGFE). The MGFE has been thoroughly studied in glasses with conventional glass-formers (B2O3, SiO2, P2O5, GeO2), yet there are scarce reports regarding the glass systems where a conventional glass-former is substituted by the conditional one, such as V2O5 and Nb2O5.1, 2 In this work, glasses of the quaternary system 35Na2O–10V2O5–(55 – x)P2O5–xNb2O5, with x in mol%, were prepared and investigated in order to verify the MGFE in the presence of two conditional glass formers, Nb2O5 and V2O5. The latter is added due to its stabilizing effect on the glass structure, as it is involved in the glass network formation and its fraction is kept constant. The glasses are synthesized by the melt-quenching method and the parameters of synthesis are optimized to obtain the desired products whose amorphous character is confirmed by PXRD. The glass transition temperatures are determined by DTA, while their (micro)structural properties are evaluated by SEM- EDS analysis and infrared spectroscopy. The electrical properties of prepared glasses are studied by impedance spectroscopy (IS) in a wide frequency (0.01 Hz – 1 MHz) and temperature (-90 °C – 240 °C) range. The correlation between the structural changes occurring upon glass-formers exchange, and certain physico-chemical properties of these glasses is discussed in detail. 1. M. Saad, W. Stambouli, N. Sdiri, H. Elhouichet, Mater. Res. Bull. 89 (2017) 224–231. 2. S. Renka, L. Pavić, G. Tricot, P. Mošner, L. Koudelka, A. Moguš-Milanković, A. Šantić, Phys. Chem. Chem. Phys. 23 (2021) 9761–9772.

Phosphate glasses ; Structural properties ; Electrical properties ; Impedance spectroscopy

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