engleski

The one with crystallization. Microstructure of oxide glass-ceramics.

Oxide glasses have functional properties that make them attractive for various applications, from optics and laser technology to nuclear waste immobilization and biomedicine. In particular, sodium phosphate-based glasses have emerged as potential candidates for use as solid-state electrolytes. Due to the incorporation of alkali oxides into the phosphate network, these glasses exhibit unique peculiarities, among which electrical transport attracts much attention. Furthermore, the addition of oxides such as Nb2O5, V2O5, and/or Al2O3, ZnO, affects the glass structure, which in turn impacts electrical transport and manifests itself as, for example, the mixed glass-former effect, mixed transition-ion effect, and/or the mixed ion-polaron effect, depending on composition and type of charge carriers. Although glassy materials have many advantages, their low electrical conductivity often limits their application. A flexible method to improve their performance is thermally induced crystallization resulting in composite materials, so-called glass-ceramics, in which single or various crystalline phases are embedded in a glassy matrix and, as such, offer improved properties compared to analog glass. Glass-ceramics can also be prepared by unwanted spontaneous crystallization during melt cooling procedure. In this study, sodium phosphate-based glass-ceramics with different incorporated oxides (Nb2O5, V2O5, and/or Al2O3) were prepared by spontaneous crystallization during melt-quenching of target compositions from the edge of the glass-forming region. Their micro(structural) properties were investigated by PXRD and SEM-EDS, and obtained results are correlated with electrical properties studied through impedance spectroscopy (IS). The micro- and nano-scale features were under scrutiny using SEM-EDS analysis, qualitative and quantitative, utilizing Axia ChemiSEM Microscope System. Different setups in high/low vacuum are applied along with detectors such as ETD, CBS-BD mode and EDS coloring mapping for visualization of elemental distribution. The obtained results allowed us to have better insight into the crystallization processes and the resulting crystalline phases embedded in an amorphous matrix, which is also confirmed by PXRD and ultimately affects electrical transport. The analysis of the (micro)structure-property relationship contributes significantly to a better understanding of the changes that occur in these materials, which promotes their use in new technologies.

Glass ceramics ; Oxide glasses ; SEM-EDS

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