Naslov
Mixed ion-polaron transport in ZnO-WO3-P2O5 glasses containing Na2O and Li2O

Autori
Šantić, Ana ; Nikolić, Juraj ; Pajić, Damir ; Dragović, Jure ; Mošner, Petr ; Koudelka, Ladislav ; Moguš-Milanković, Andrea

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of abstracts of the "9th International Conference on Broadband Dielectric Spectroscopy and its Applications" / Labardi, M. ; Tombari, E. - Pisa : Institute for Chemical and Physical Processes, Pisa, 2016, P-51

ISBN
97888652283547

Skup
9th International Conference on Broadband Dielectric Spectroscopy and its Applications

Mjesto i datum
Pisa, Italija, 11.09.2016. - 16.09.2016

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Oxide glasses; Mixed ion-polaron conductivity

Sažetak
Oxide glasses containing mobile alkali ions and transition metal oxides (TMO) such as WO3, Fe2O3, V2O5, MoO3 exhibit mixed ion-polaron conductivity. While ionic conductivity depends on the concentration and mobility of alkali ions, polaronic transport follows the small polaron hopping mechanism and it is mainly controlled by the overall amount of TMO and fraction of TM ions in different valence states. The aim of this study was to investigate the mechanism of electrical transport in glasses containing WO3 and Na+/Li+ ions, namely, glasses from series xWO3-(30-0.5x)Na2O-(30-0.5x)ZnO-40P2O5, 0≤x≤60 (mol%) and xWO3-(30-0.5x)Li2O-(30-0.5x)ZnO-40P2O5, 0≤x≤40 (mol%). Electrical properties of glasses were measured by impedance spectroscopy in the wide frequency and temperature range (0.01 Hz - 2 MHz, 303 - 513 K). The fraction of tungsten ions in different valence states, W5+/Wtot, was determined from the temperature dependence of magnetization, measured with SQUID magnetometer, and analysed using the Curie constant attributed to the isolated paramagnetic centres W5+. Electrical conductivity of xWO3-(30-0.5x)Na2O-(30-0.5x)ZnO-40P2O5 glasses is almost constant up to x=30 mol%, whereas for glasses with higher WO3 content conductivity increases drastically due to an increase in polaronic contribution. On the other hand, glasses from xWO3-(30-0.5x)Li2O-(30-0.5x)ZnO-40P2O5 series exhibit minimum in conductivity at approximately x=20 mol%. This phenomenon can be related to the coupling of ionic and polaronic transport which decreases effective mobility of both types of charge carriers. Comparing glasses between the two series, in the compositional region where the ionic conductivity prevails (up to x=30 mol% WO3), glasses containing Na+ show higher conductivities than glasses with Li+ despite the smaller size of the later ion. This result suggests that lithium ions have lower mobility in these glasses due to a strong interactions with the structural units in the glass network. The reverse trend for glasses with 40 mol% of WO3 is attributed entirely to the polaronic transport since glass containing Li2O has higher fraction of W5+ ions (W5+/Wtot=1.3%) than the glass containig Na2O (W5+/Wtot=0.8%).

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA